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 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); 346 sb->s_dirt = 1; 347 mark_buffer_dirty(EXT2_SB(sb)->s_sbh); 348 } 349 350 /* 351 * ext2_xattr_set() 352 * 353 * Create, replace or remove an extended attribute for this inode. Buffer 354 * is NULL to remove an existing extended attribute, and non-NULL to 355 * either replace an existing extended attribute, or create a new extended 356 * attribute. The flags XATTR_REPLACE and XATTR_CREATE 357 * specify that an extended attribute must exist and must not exist 358 * previous to the call, respectively. 359 * 360 * Returns 0, or a negative error number on failure. 361 */ 362 int 363 ext2_xattr_set(struct inode *inode, int name_index, const char *name, 364 const void *value, size_t value_len, int flags) 365 { 366 struct super_block *sb = inode->i_sb; 367 struct buffer_head *bh = NULL; 368 struct ext2_xattr_header *header = NULL; 369 struct ext2_xattr_entry *here, *last; 370 size_t name_len, free, min_offs = sb->s_blocksize; 371 int not_found = 1, error; 372 char *end; 373 374 /* 375 * header -- Points either into bh, or to a temporarily 376 * allocated buffer. 377 * here -- The named entry found, or the place for inserting, within 378 * the block pointed to by header. 379 * last -- Points right after the last named entry within the block 380 * pointed to by header. 381 * min_offs -- The offset of the first value (values are aligned 382 * towards the end of the block). 383 * end -- Points right after the block pointed to by header. 384 */ 385 386 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", 387 name_index, name, value, (long)value_len); 388 389 if (value == NULL) 390 value_len = 0; 391 if (name == NULL) 392 return -EINVAL; 393 name_len = strlen(name); 394 if (name_len > 255 || value_len > sb->s_blocksize) 395 return -ERANGE; 396 down_write(&EXT2_I(inode)->xattr_sem); 397 if (EXT2_I(inode)->i_file_acl) { 398 /* The inode already has an extended attribute block. */ 399 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 400 error = -EIO; 401 if (!bh) 402 goto cleanup; 403 ea_bdebug(bh, "b_count=%d, refcount=%d", 404 atomic_read(&(bh->b_count)), 405 le32_to_cpu(HDR(bh)->h_refcount)); 406 header = HDR(bh); 407 end = bh->b_data + bh->b_size; 408 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 409 header->h_blocks != cpu_to_le32(1)) { 410 bad_block: ext2_error(sb, "ext2_xattr_set", 411 "inode %ld: bad block %d", inode->i_ino, 412 EXT2_I(inode)->i_file_acl); 413 error = -EIO; 414 goto cleanup; 415 } 416 /* Find the named attribute. */ 417 here = FIRST_ENTRY(bh); 418 while (!IS_LAST_ENTRY(here)) { 419 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(here); 420 if ((char *)next >= end) 421 goto bad_block; 422 if (!here->e_value_block && here->e_value_size) { 423 size_t offs = le16_to_cpu(here->e_value_offs); 424 if (offs < min_offs) 425 min_offs = offs; 426 } 427 not_found = name_index - here->e_name_index; 428 if (!not_found) 429 not_found = name_len - here->e_name_len; 430 if (!not_found) 431 not_found = memcmp(name, here->e_name,name_len); 432 if (not_found <= 0) 433 break; 434 here = next; 435 } 436 last = here; 437 /* We still need to compute min_offs and last. */ 438 while (!IS_LAST_ENTRY(last)) { 439 struct ext2_xattr_entry *next = EXT2_XATTR_NEXT(last); 440 if ((char *)next >= end) 441 goto bad_block; 442 if (!last->e_value_block && last->e_value_size) { 443 size_t offs = le16_to_cpu(last->e_value_offs); 444 if (offs < min_offs) 445 min_offs = offs; 446 } 447 last = next; 448 } 449 450 /* Check whether we have enough space left. */ 451 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 452 } else { 453 /* We will use a new extended attribute block. */ 454 free = sb->s_blocksize - 455 sizeof(struct ext2_xattr_header) - sizeof(__u32); 456 here = last = NULL; /* avoid gcc uninitialized warning. */ 457 } 458 459 if (not_found) { 460 /* Request to remove a nonexistent attribute? */ 461 error = -ENODATA; 462 if (flags & XATTR_REPLACE) 463 goto cleanup; 464 error = 0; 465 if (value == NULL) 466 goto cleanup; 467 } else { 468 /* Request to create an existing attribute? */ 469 error = -EEXIST; 470 if (flags & XATTR_CREATE) 471 goto cleanup; 472 if (!here->e_value_block && here->e_value_size) { 473 size_t size = le32_to_cpu(here->e_value_size); 474 475 if (le16_to_cpu(here->e_value_offs) + size > 476 sb->s_blocksize || size > sb->s_blocksize) 477 goto bad_block; 478 free += EXT2_XATTR_SIZE(size); 479 } 480 free += EXT2_XATTR_LEN(name_len); 481 } 482 error = -ENOSPC; 483 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 484 goto cleanup; 485 486 /* Here we know that we can set the new attribute. */ 487 488 if (header) { 489 struct mb_cache_entry *ce; 490 491 /* assert(header == HDR(bh)); */ 492 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, 493 bh->b_blocknr); 494 lock_buffer(bh); 495 if (header->h_refcount == cpu_to_le32(1)) { 496 ea_bdebug(bh, "modifying in-place"); 497 if (ce) 498 mb_cache_entry_free(ce); 499 /* keep the buffer locked while modifying it. */ 500 } else { 501 int offset; 502 503 if (ce) 504 mb_cache_entry_release(ce); 505 unlock_buffer(bh); 506 ea_bdebug(bh, "cloning"); 507 header = kmalloc(bh->b_size, GFP_KERNEL); 508 error = -ENOMEM; 509 if (header == NULL) 510 goto cleanup; 511 memcpy(header, HDR(bh), bh->b_size); 512 header->h_refcount = cpu_to_le32(1); 513 514 offset = (char *)here - bh->b_data; 515 here = ENTRY((char *)header + offset); 516 offset = (char *)last - bh->b_data; 517 last = ENTRY((char *)header + offset); 518 } 519 } else { 520 /* Allocate a buffer where we construct the new block. */ 521 header = kzalloc(sb->s_blocksize, GFP_KERNEL); 522 error = -ENOMEM; 523 if (header == NULL) 524 goto cleanup; 525 end = (char *)header + sb->s_blocksize; 526 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 527 header->h_blocks = header->h_refcount = cpu_to_le32(1); 528 last = here = ENTRY(header+1); 529 } 530 531 /* Iff we are modifying the block in-place, bh is locked here. */ 532 533 if (not_found) { 534 /* Insert the new name. */ 535 size_t size = EXT2_XATTR_LEN(name_len); 536 size_t rest = (char *)last - (char *)here; 537 memmove((char *)here + size, here, rest); 538 memset(here, 0, size); 539 here->e_name_index = name_index; 540 here->e_name_len = name_len; 541 memcpy(here->e_name, name, name_len); 542 } else { 543 if (!here->e_value_block && here->e_value_size) { 544 char *first_val = (char *)header + min_offs; 545 size_t offs = le16_to_cpu(here->e_value_offs); 546 char *val = (char *)header + offs; 547 size_t size = EXT2_XATTR_SIZE( 548 le32_to_cpu(here->e_value_size)); 549 550 if (size == EXT2_XATTR_SIZE(value_len)) { 551 /* The old and the new value have the same 552 size. Just replace. */ 553 here->e_value_size = cpu_to_le32(value_len); 554 memset(val + size - EXT2_XATTR_PAD, 0, 555 EXT2_XATTR_PAD); /* Clear pad bytes. */ 556 memcpy(val, value, value_len); 557 goto skip_replace; 558 } 559 560 /* Remove the old value. */ 561 memmove(first_val + size, first_val, val - first_val); 562 memset(first_val, 0, size); 563 here->e_value_offs = 0; 564 min_offs += size; 565 566 /* Adjust all value offsets. */ 567 last = ENTRY(header+1); 568 while (!IS_LAST_ENTRY(last)) { 569 size_t o = le16_to_cpu(last->e_value_offs); 570 if (!last->e_value_block && o < offs) 571 last->e_value_offs = 572 cpu_to_le16(o + size); 573 last = EXT2_XATTR_NEXT(last); 574 } 575 } 576 if (value == NULL) { 577 /* Remove the old name. */ 578 size_t size = EXT2_XATTR_LEN(name_len); 579 last = ENTRY((char *)last - size); 580 memmove(here, (char*)here + size, 581 (char*)last - (char*)here); 582 memset(last, 0, size); 583 } 584 } 585 586 if (value != NULL) { 587 /* Insert the new value. */ 588 here->e_value_size = cpu_to_le32(value_len); 589 if (value_len) { 590 size_t size = EXT2_XATTR_SIZE(value_len); 591 char *val = (char *)header + min_offs - size; 592 here->e_value_offs = 593 cpu_to_le16((char *)val - (char *)header); 594 memset(val + size - EXT2_XATTR_PAD, 0, 595 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 596 memcpy(val, value, value_len); 597 } 598 } 599 600 skip_replace: 601 if (IS_LAST_ENTRY(ENTRY(header+1))) { 602 /* This block is now empty. */ 603 if (bh && header == HDR(bh)) 604 unlock_buffer(bh); /* we were modifying in-place. */ 605 error = ext2_xattr_set2(inode, bh, NULL); 606 } else { 607 ext2_xattr_rehash(header, here); 608 if (bh && header == HDR(bh)) 609 unlock_buffer(bh); /* we were modifying in-place. */ 610 error = ext2_xattr_set2(inode, bh, header); 611 } 612 613 cleanup: 614 brelse(bh); 615 if (!(bh && header == HDR(bh))) 616 kfree(header); 617 up_write(&EXT2_I(inode)->xattr_sem); 618 619 return error; 620 } 621 622 /* 623 * Second half of ext2_xattr_set(): Update the file system. 624 */ 625 static int 626 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 627 struct ext2_xattr_header *header) 628 { 629 struct super_block *sb = inode->i_sb; 630 struct buffer_head *new_bh = NULL; 631 int error; 632 633 if (header) { 634 new_bh = ext2_xattr_cache_find(inode, header); 635 if (new_bh) { 636 /* We found an identical block in the cache. */ 637 if (new_bh == old_bh) { 638 ea_bdebug(new_bh, "keeping this block"); 639 } else { 640 /* The old block is released after updating 641 the inode. */ 642 ea_bdebug(new_bh, "reusing block"); 643 644 error = -EDQUOT; 645 if (DQUOT_ALLOC_BLOCK(inode, 1)) { 646 unlock_buffer(new_bh); 647 goto cleanup; 648 } 649 HDR(new_bh)->h_refcount = cpu_to_le32(1 + 650 le32_to_cpu(HDR(new_bh)->h_refcount)); 651 ea_bdebug(new_bh, "refcount now=%d", 652 le32_to_cpu(HDR(new_bh)->h_refcount)); 653 } 654 unlock_buffer(new_bh); 655 } else if (old_bh && header == HDR(old_bh)) { 656 /* Keep this block. No need to lock the block as we 657 don't need to change the reference count. */ 658 new_bh = old_bh; 659 get_bh(new_bh); 660 ext2_xattr_cache_insert(new_bh); 661 } else { 662 /* We need to allocate a new block */ 663 int goal = le32_to_cpu(EXT2_SB(sb)->s_es-> 664 s_first_data_block) + 665 EXT2_I(inode)->i_block_group * 666 EXT2_BLOCKS_PER_GROUP(sb); 667 int block = ext2_new_block(inode, goal, 668 NULL, NULL, &error); 669 if (error) 670 goto cleanup; 671 ea_idebug(inode, "creating block %d", block); 672 673 new_bh = sb_getblk(sb, block); 674 if (!new_bh) { 675 ext2_free_blocks(inode, block, 1); 676 error = -EIO; 677 goto cleanup; 678 } 679 lock_buffer(new_bh); 680 memcpy(new_bh->b_data, header, new_bh->b_size); 681 set_buffer_uptodate(new_bh); 682 unlock_buffer(new_bh); 683 ext2_xattr_cache_insert(new_bh); 684 685 ext2_xattr_update_super_block(sb); 686 } 687 mark_buffer_dirty(new_bh); 688 if (IS_SYNC(inode)) { 689 sync_dirty_buffer(new_bh); 690 error = -EIO; 691 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 692 goto cleanup; 693 } 694 } 695 696 /* Update the inode. */ 697 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 698 inode->i_ctime = CURRENT_TIME_SEC; 699 if (IS_SYNC(inode)) { 700 error = ext2_sync_inode (inode); 701 /* In case sync failed due to ENOSPC the inode was actually 702 * written (only some dirty data were not) so we just proceed 703 * as if nothing happened and cleanup the unused block */ 704 if (error && error != -ENOSPC) { 705 if (new_bh && new_bh != old_bh) 706 DQUOT_FREE_BLOCK(inode, 1); 707 goto cleanup; 708 } 709 } else 710 mark_inode_dirty(inode); 711 712 error = 0; 713 if (old_bh && old_bh != new_bh) { 714 struct mb_cache_entry *ce; 715 716 /* 717 * If there was an old block and we are no longer using it, 718 * release the old block. 719 */ 720 ce = mb_cache_entry_get(ext2_xattr_cache, old_bh->b_bdev, 721 old_bh->b_blocknr); 722 lock_buffer(old_bh); 723 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 724 /* Free the old block. */ 725 if (ce) 726 mb_cache_entry_free(ce); 727 ea_bdebug(old_bh, "freeing"); 728 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 729 /* We let our caller release old_bh, so we 730 * need to duplicate the buffer before. */ 731 get_bh(old_bh); 732 bforget(old_bh); 733 } else { 734 /* Decrement the refcount only. */ 735 HDR(old_bh)->h_refcount = cpu_to_le32( 736 le32_to_cpu(HDR(old_bh)->h_refcount) - 1); 737 if (ce) 738 mb_cache_entry_release(ce); 739 DQUOT_FREE_BLOCK(inode, 1); 740 mark_buffer_dirty(old_bh); 741 ea_bdebug(old_bh, "refcount now=%d", 742 le32_to_cpu(HDR(old_bh)->h_refcount)); 743 } 744 unlock_buffer(old_bh); 745 } 746 747 cleanup: 748 brelse(new_bh); 749 750 return error; 751 } 752 753 /* 754 * ext2_xattr_delete_inode() 755 * 756 * Free extended attribute resources associated with this inode. This 757 * is called immediately before an inode is freed. 758 */ 759 void 760 ext2_xattr_delete_inode(struct inode *inode) 761 { 762 struct buffer_head *bh = NULL; 763 struct mb_cache_entry *ce; 764 765 down_write(&EXT2_I(inode)->xattr_sem); 766 if (!EXT2_I(inode)->i_file_acl) 767 goto cleanup; 768 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 769 if (!bh) { 770 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 771 "inode %ld: block %d read error", inode->i_ino, 772 EXT2_I(inode)->i_file_acl); 773 goto cleanup; 774 } 775 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 776 if (HDR(bh)->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 777 HDR(bh)->h_blocks != cpu_to_le32(1)) { 778 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 779 "inode %ld: bad block %d", inode->i_ino, 780 EXT2_I(inode)->i_file_acl); 781 goto cleanup; 782 } 783 ce = mb_cache_entry_get(ext2_xattr_cache, bh->b_bdev, bh->b_blocknr); 784 lock_buffer(bh); 785 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 786 if (ce) 787 mb_cache_entry_free(ce); 788 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 789 get_bh(bh); 790 bforget(bh); 791 unlock_buffer(bh); 792 } else { 793 HDR(bh)->h_refcount = cpu_to_le32( 794 le32_to_cpu(HDR(bh)->h_refcount) - 1); 795 if (ce) 796 mb_cache_entry_release(ce); 797 ea_bdebug(bh, "refcount now=%d", 798 le32_to_cpu(HDR(bh)->h_refcount)); 799 unlock_buffer(bh); 800 mark_buffer_dirty(bh); 801 if (IS_SYNC(inode)) 802 sync_dirty_buffer(bh); 803 DQUOT_FREE_BLOCK(inode, 1); 804 } 805 EXT2_I(inode)->i_file_acl = 0; 806 807 cleanup: 808 brelse(bh); 809 up_write(&EXT2_I(inode)->xattr_sem); 810 } 811 812 /* 813 * ext2_xattr_put_super() 814 * 815 * This is called when a file system is unmounted. 816 */ 817 void 818 ext2_xattr_put_super(struct super_block *sb) 819 { 820 mb_cache_shrink(sb->s_bdev); 821 } 822 823 824 /* 825 * ext2_xattr_cache_insert() 826 * 827 * Create a new entry in the extended attribute cache, and insert 828 * it unless such an entry is already in the cache. 829 * 830 * Returns 0, or a negative error number on failure. 831 */ 832 static int 833 ext2_xattr_cache_insert(struct buffer_head *bh) 834 { 835 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 836 struct mb_cache_entry *ce; 837 int error; 838 839 ce = mb_cache_entry_alloc(ext2_xattr_cache); 840 if (!ce) 841 return -ENOMEM; 842 error = mb_cache_entry_insert(ce, bh->b_bdev, bh->b_blocknr, &hash); 843 if (error) { 844 mb_cache_entry_free(ce); 845 if (error == -EBUSY) { 846 ea_bdebug(bh, "already in cache (%d cache entries)", 847 atomic_read(&ext2_xattr_cache->c_entry_count)); 848 error = 0; 849 } 850 } else { 851 ea_bdebug(bh, "inserting [%x] (%d cache entries)", (int)hash, 852 atomic_read(&ext2_xattr_cache->c_entry_count)); 853 mb_cache_entry_release(ce); 854 } 855 return error; 856 } 857 858 /* 859 * ext2_xattr_cmp() 860 * 861 * Compare two extended attribute blocks for equality. 862 * 863 * Returns 0 if the blocks are equal, 1 if they differ, and 864 * a negative error number on errors. 865 */ 866 static int 867 ext2_xattr_cmp(struct ext2_xattr_header *header1, 868 struct ext2_xattr_header *header2) 869 { 870 struct ext2_xattr_entry *entry1, *entry2; 871 872 entry1 = ENTRY(header1+1); 873 entry2 = ENTRY(header2+1); 874 while (!IS_LAST_ENTRY(entry1)) { 875 if (IS_LAST_ENTRY(entry2)) 876 return 1; 877 if (entry1->e_hash != entry2->e_hash || 878 entry1->e_name_index != entry2->e_name_index || 879 entry1->e_name_len != entry2->e_name_len || 880 entry1->e_value_size != entry2->e_value_size || 881 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 882 return 1; 883 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 884 return -EIO; 885 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 886 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 887 le32_to_cpu(entry1->e_value_size))) 888 return 1; 889 890 entry1 = EXT2_XATTR_NEXT(entry1); 891 entry2 = EXT2_XATTR_NEXT(entry2); 892 } 893 if (!IS_LAST_ENTRY(entry2)) 894 return 1; 895 return 0; 896 } 897 898 /* 899 * ext2_xattr_cache_find() 900 * 901 * Find an identical extended attribute block. 902 * 903 * Returns a locked buffer head to the block found, or NULL if such 904 * a block was not found or an error occurred. 905 */ 906 static struct buffer_head * 907 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 908 { 909 __u32 hash = le32_to_cpu(header->h_hash); 910 struct mb_cache_entry *ce; 911 912 if (!header->h_hash) 913 return NULL; /* never share */ 914 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 915 again: 916 ce = mb_cache_entry_find_first(ext2_xattr_cache, 0, 917 inode->i_sb->s_bdev, hash); 918 while (ce) { 919 struct buffer_head *bh; 920 921 if (IS_ERR(ce)) { 922 if (PTR_ERR(ce) == -EAGAIN) 923 goto again; 924 break; 925 } 926 927 bh = sb_bread(inode->i_sb, ce->e_block); 928 if (!bh) { 929 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 930 "inode %ld: block %ld read error", 931 inode->i_ino, (unsigned long) ce->e_block); 932 } else { 933 lock_buffer(bh); 934 if (le32_to_cpu(HDR(bh)->h_refcount) > 935 EXT2_XATTR_REFCOUNT_MAX) { 936 ea_idebug(inode, "block %ld refcount %d>%d", 937 (unsigned long) ce->e_block, 938 le32_to_cpu(HDR(bh)->h_refcount), 939 EXT2_XATTR_REFCOUNT_MAX); 940 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 941 ea_bdebug(bh, "b_count=%d", 942 atomic_read(&(bh->b_count))); 943 mb_cache_entry_release(ce); 944 return bh; 945 } 946 unlock_buffer(bh); 947 brelse(bh); 948 } 949 ce = mb_cache_entry_find_next(ce, 0, inode->i_sb->s_bdev, hash); 950 } 951 return NULL; 952 } 953 954 #define NAME_HASH_SHIFT 5 955 #define VALUE_HASH_SHIFT 16 956 957 /* 958 * ext2_xattr_hash_entry() 959 * 960 * Compute the hash of an extended attribute. 961 */ 962 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 963 struct ext2_xattr_entry *entry) 964 { 965 __u32 hash = 0; 966 char *name = entry->e_name; 967 int n; 968 969 for (n=0; n < entry->e_name_len; n++) { 970 hash = (hash << NAME_HASH_SHIFT) ^ 971 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 972 *name++; 973 } 974 975 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 976 __le32 *value = (__le32 *)((char *)header + 977 le16_to_cpu(entry->e_value_offs)); 978 for (n = (le32_to_cpu(entry->e_value_size) + 979 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 980 hash = (hash << VALUE_HASH_SHIFT) ^ 981 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 982 le32_to_cpu(*value++); 983 } 984 } 985 entry->e_hash = cpu_to_le32(hash); 986 } 987 988 #undef NAME_HASH_SHIFT 989 #undef VALUE_HASH_SHIFT 990 991 #define BLOCK_HASH_SHIFT 16 992 993 /* 994 * ext2_xattr_rehash() 995 * 996 * Re-compute the extended attribute hash value after an entry has changed. 997 */ 998 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 999 struct ext2_xattr_entry *entry) 1000 { 1001 struct ext2_xattr_entry *here; 1002 __u32 hash = 0; 1003 1004 ext2_xattr_hash_entry(header, entry); 1005 here = ENTRY(header+1); 1006 while (!IS_LAST_ENTRY(here)) { 1007 if (!here->e_hash) { 1008 /* Block is not shared if an entry's hash value == 0 */ 1009 hash = 0; 1010 break; 1011 } 1012 hash = (hash << BLOCK_HASH_SHIFT) ^ 1013 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1014 le32_to_cpu(here->e_hash); 1015 here = EXT2_XATTR_NEXT(here); 1016 } 1017 header->h_hash = cpu_to_le32(hash); 1018 } 1019 1020 #undef BLOCK_HASH_SHIFT 1021 1022 int __init 1023 init_ext2_xattr(void) 1024 { 1025 ext2_xattr_cache = mb_cache_create("ext2_xattr", NULL, 1026 sizeof(struct mb_cache_entry) + 1027 sizeof(((struct mb_cache_entry *) 0)->e_indexes[0]), 1, 6); 1028 if (!ext2_xattr_cache) 1029 return -ENOMEM; 1030 return 0; 1031 } 1032 1033 void 1034 exit_ext2_xattr(void) 1035 { 1036 mb_cache_destroy(ext2_xattr_cache); 1037 } 1038