1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * linux/fs/ext2/xattr.c 4 * 5 * Copyright (C) 2001-2003 Andreas Gruenbacher <agruen@suse.de> 6 * 7 * Fix by Harrison Xing <harrison@mountainviewdata.com>. 8 * Extended attributes for symlinks and special files added per 9 * suggestion of Luka Renko <luka.renko@hermes.si>. 10 * xattr consolidation Copyright (c) 2004 James Morris <jmorris@redhat.com>, 11 * Red Hat Inc. 12 * 13 */ 14 15 /* 16 * Extended attributes are stored on disk blocks allocated outside of 17 * any inode. The i_file_acl field is then made to point to this allocated 18 * block. If all extended attributes of an inode are identical, these 19 * inodes may share the same extended attribute block. Such situations 20 * are automatically detected by keeping a cache of recent attribute block 21 * numbers and hashes over the block's contents in memory. 22 * 23 * 24 * Extended attribute block layout: 25 * 26 * +------------------+ 27 * | header | 28 * | entry 1 | | 29 * | entry 2 | | growing downwards 30 * | entry 3 | v 31 * | four null bytes | 32 * | . . . | 33 * | value 1 | ^ 34 * | value 3 | | growing upwards 35 * | value 2 | | 36 * +------------------+ 37 * 38 * The block header is followed by multiple entry descriptors. These entry 39 * descriptors are variable in size, and aligned to EXT2_XATTR_PAD 40 * byte boundaries. The entry descriptors are sorted by attribute name, 41 * so that two extended attribute blocks can be compared efficiently. 42 * 43 * Attribute values are aligned to the end of the block, stored in 44 * no specific order. They are also padded to EXT2_XATTR_PAD byte 45 * boundaries. No additional gaps are left between them. 46 * 47 * Locking strategy 48 * ---------------- 49 * EXT2_I(inode)->i_file_acl is protected by EXT2_I(inode)->xattr_sem. 50 * EA blocks are only changed if they are exclusive to an inode, so 51 * holding xattr_sem also means that nothing but the EA block's reference 52 * count will change. Multiple writers to an EA block are synchronized 53 * by the bh lock. No more than a single bh lock is held at any time 54 * to avoid deadlocks. 55 */ 56 57 #include <linux/buffer_head.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 <linux/security.h> 64 #include "ext2.h" 65 #include "xattr.h" 66 #include "acl.h" 67 68 #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) 69 #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) 70 #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) 71 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) 72 73 #ifdef EXT2_XATTR_DEBUG 74 # define ea_idebug(inode, f...) do { \ 75 printk(KERN_DEBUG "inode %s:%ld: ", \ 76 inode->i_sb->s_id, inode->i_ino); \ 77 printk(f); \ 78 printk("\n"); \ 79 } while (0) 80 # define ea_bdebug(bh, f...) do { \ 81 printk(KERN_DEBUG "block %pg:%lu: ", \ 82 bh->b_bdev, (unsigned long) bh->b_blocknr); \ 83 printk(f); \ 84 printk("\n"); \ 85 } while (0) 86 #else 87 # define ea_idebug(f...) 88 # define ea_bdebug(f...) 89 #endif 90 91 static int ext2_xattr_set2(struct inode *, struct buffer_head *, 92 struct ext2_xattr_header *); 93 94 static int ext2_xattr_cache_insert(struct mb_cache *, struct buffer_head *); 95 static struct buffer_head *ext2_xattr_cache_find(struct inode *, 96 struct ext2_xattr_header *); 97 static void ext2_xattr_rehash(struct ext2_xattr_header *, 98 struct ext2_xattr_entry *); 99 100 static const struct xattr_handler *ext2_xattr_handler_map[] = { 101 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, 102 #ifdef CONFIG_EXT2_FS_POSIX_ACL 103 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, 104 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, 105 #endif 106 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, 107 #ifdef CONFIG_EXT2_FS_SECURITY 108 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, 109 #endif 110 }; 111 112 const struct xattr_handler *ext2_xattr_handlers[] = { 113 &ext2_xattr_user_handler, 114 &ext2_xattr_trusted_handler, 115 #ifdef CONFIG_EXT2_FS_POSIX_ACL 116 &posix_acl_access_xattr_handler, 117 &posix_acl_default_xattr_handler, 118 #endif 119 #ifdef CONFIG_EXT2_FS_SECURITY 120 &ext2_xattr_security_handler, 121 #endif 122 NULL 123 }; 124 125 #define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache) 126 127 static inline const struct xattr_handler * 128 ext2_xattr_handler(int name_index) 129 { 130 const struct xattr_handler *handler = NULL; 131 132 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) 133 handler = ext2_xattr_handler_map[name_index]; 134 return handler; 135 } 136 137 static bool 138 ext2_xattr_header_valid(struct ext2_xattr_header *header) 139 { 140 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 141 header->h_blocks != cpu_to_le32(1)) 142 return false; 143 144 return true; 145 } 146 147 static bool 148 ext2_xattr_entry_valid(struct ext2_xattr_entry *entry, 149 char *end, size_t end_offs) 150 { 151 struct ext2_xattr_entry *next; 152 size_t size; 153 154 next = EXT2_XATTR_NEXT(entry); 155 if ((char *)next >= end) 156 return false; 157 158 if (entry->e_value_block != 0) 159 return false; 160 161 size = le32_to_cpu(entry->e_value_size); 162 if (size > end_offs || 163 le16_to_cpu(entry->e_value_offs) + size > end_offs) 164 return false; 165 166 return true; 167 } 168 169 static int 170 ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name, 171 struct ext2_xattr_entry *entry) 172 { 173 int cmp; 174 175 cmp = name_index - entry->e_name_index; 176 if (!cmp) 177 cmp = name_len - entry->e_name_len; 178 if (!cmp) 179 cmp = memcmp(name, entry->e_name, name_len); 180 181 return cmp; 182 } 183 184 /* 185 * ext2_xattr_get() 186 * 187 * Copy an extended attribute into the buffer 188 * provided, or compute the buffer size required. 189 * Buffer is NULL to compute the size of the buffer required. 190 * 191 * Returns a negative error number on failure, or the number of bytes 192 * used / required on success. 193 */ 194 int 195 ext2_xattr_get(struct inode *inode, int name_index, const char *name, 196 void *buffer, size_t buffer_size) 197 { 198 struct buffer_head *bh = NULL; 199 struct ext2_xattr_entry *entry; 200 size_t name_len, size; 201 char *end; 202 int error, not_found; 203 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 204 205 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", 206 name_index, name, buffer, (long)buffer_size); 207 208 if (name == NULL) 209 return -EINVAL; 210 name_len = strlen(name); 211 if (name_len > 255) 212 return -ERANGE; 213 214 down_read(&EXT2_I(inode)->xattr_sem); 215 error = -ENODATA; 216 if (!EXT2_I(inode)->i_file_acl) 217 goto cleanup; 218 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 219 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 220 error = -EIO; 221 if (!bh) 222 goto cleanup; 223 ea_bdebug(bh, "b_count=%d, refcount=%d", 224 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 225 end = bh->b_data + bh->b_size; 226 if (!ext2_xattr_header_valid(HDR(bh))) { 227 bad_block: 228 ext2_error(inode->i_sb, "ext2_xattr_get", 229 "inode %ld: bad block %d", inode->i_ino, 230 EXT2_I(inode)->i_file_acl); 231 error = -EIO; 232 goto cleanup; 233 } 234 235 /* find named attribute */ 236 entry = FIRST_ENTRY(bh); 237 while (!IS_LAST_ENTRY(entry)) { 238 if (!ext2_xattr_entry_valid(entry, end, 239 inode->i_sb->s_blocksize)) 240 goto bad_block; 241 242 not_found = ext2_xattr_cmp_entry(name_index, name_len, name, 243 entry); 244 if (!not_found) 245 goto found; 246 if (not_found < 0) 247 break; 248 249 entry = EXT2_XATTR_NEXT(entry); 250 } 251 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 252 ea_idebug(inode, "cache insert failed"); 253 error = -ENODATA; 254 goto cleanup; 255 found: 256 size = le32_to_cpu(entry->e_value_size); 257 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 258 ea_idebug(inode, "cache insert failed"); 259 if (buffer) { 260 error = -ERANGE; 261 if (size > buffer_size) 262 goto cleanup; 263 /* return value of attribute */ 264 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), 265 size); 266 } 267 error = size; 268 269 cleanup: 270 brelse(bh); 271 up_read(&EXT2_I(inode)->xattr_sem); 272 273 return error; 274 } 275 276 /* 277 * ext2_xattr_list() 278 * 279 * Copy a list of attribute names into the buffer 280 * provided, or compute the buffer size required. 281 * Buffer is NULL to compute the size of the buffer required. 282 * 283 * Returns a negative error number on failure, or the number of bytes 284 * used / required on success. 285 */ 286 static int 287 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) 288 { 289 struct inode *inode = d_inode(dentry); 290 struct buffer_head *bh = NULL; 291 struct ext2_xattr_entry *entry; 292 char *end; 293 size_t rest = buffer_size; 294 int error; 295 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 296 297 ea_idebug(inode, "buffer=%p, buffer_size=%ld", 298 buffer, (long)buffer_size); 299 300 down_read(&EXT2_I(inode)->xattr_sem); 301 error = 0; 302 if (!EXT2_I(inode)->i_file_acl) 303 goto cleanup; 304 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 305 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 306 error = -EIO; 307 if (!bh) 308 goto cleanup; 309 ea_bdebug(bh, "b_count=%d, refcount=%d", 310 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 311 end = bh->b_data + bh->b_size; 312 if (!ext2_xattr_header_valid(HDR(bh))) { 313 bad_block: 314 ext2_error(inode->i_sb, "ext2_xattr_list", 315 "inode %ld: bad block %d", inode->i_ino, 316 EXT2_I(inode)->i_file_acl); 317 error = -EIO; 318 goto cleanup; 319 } 320 321 /* check the on-disk data structure */ 322 entry = FIRST_ENTRY(bh); 323 while (!IS_LAST_ENTRY(entry)) { 324 if (!ext2_xattr_entry_valid(entry, end, 325 inode->i_sb->s_blocksize)) 326 goto bad_block; 327 entry = EXT2_XATTR_NEXT(entry); 328 } 329 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 330 ea_idebug(inode, "cache insert failed"); 331 332 /* list the attribute names */ 333 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); 334 entry = EXT2_XATTR_NEXT(entry)) { 335 const struct xattr_handler *handler = 336 ext2_xattr_handler(entry->e_name_index); 337 338 if (handler && (!handler->list || handler->list(dentry))) { 339 const char *prefix = handler->prefix ?: handler->name; 340 size_t prefix_len = strlen(prefix); 341 size_t size = prefix_len + entry->e_name_len + 1; 342 343 if (buffer) { 344 if (size > rest) { 345 error = -ERANGE; 346 goto cleanup; 347 } 348 memcpy(buffer, prefix, prefix_len); 349 buffer += prefix_len; 350 memcpy(buffer, entry->e_name, entry->e_name_len); 351 buffer += entry->e_name_len; 352 *buffer++ = 0; 353 } 354 rest -= size; 355 } 356 } 357 error = buffer_size - rest; /* total size */ 358 359 cleanup: 360 brelse(bh); 361 up_read(&EXT2_I(inode)->xattr_sem); 362 363 return error; 364 } 365 366 /* 367 * Inode operation listxattr() 368 * 369 * d_inode(dentry)->i_mutex: don't care 370 */ 371 ssize_t 372 ext2_listxattr(struct dentry *dentry, char *buffer, size_t size) 373 { 374 return ext2_xattr_list(dentry, buffer, size); 375 } 376 377 /* 378 * If the EXT2_FEATURE_COMPAT_EXT_ATTR feature of this file system is 379 * not set, set it. 380 */ 381 static void ext2_xattr_update_super_block(struct super_block *sb) 382 { 383 if (EXT2_HAS_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR)) 384 return; 385 386 spin_lock(&EXT2_SB(sb)->s_lock); 387 ext2_update_dynamic_rev(sb); 388 EXT2_SET_COMPAT_FEATURE(sb, EXT2_FEATURE_COMPAT_EXT_ATTR); 389 spin_unlock(&EXT2_SB(sb)->s_lock); 390 mark_buffer_dirty(EXT2_SB(sb)->s_sbh); 391 } 392 393 /* 394 * ext2_xattr_set() 395 * 396 * Create, replace or remove an extended attribute for this inode. Value 397 * is NULL to remove an existing extended attribute, and non-NULL to 398 * either replace an existing extended attribute, or create a new extended 399 * attribute. The flags XATTR_REPLACE and XATTR_CREATE 400 * specify that an extended attribute must exist and must not exist 401 * previous to the call, respectively. 402 * 403 * Returns 0, or a negative error number on failure. 404 */ 405 int 406 ext2_xattr_set(struct inode *inode, int name_index, const char *name, 407 const void *value, size_t value_len, int flags) 408 { 409 struct super_block *sb = inode->i_sb; 410 struct buffer_head *bh = NULL; 411 struct ext2_xattr_header *header = NULL; 412 struct ext2_xattr_entry *here = NULL, *last = NULL; 413 size_t name_len, free, min_offs = sb->s_blocksize; 414 int not_found = 1, error; 415 char *end; 416 417 /* 418 * header -- Points either into bh, or to a temporarily 419 * allocated buffer. 420 * here -- The named entry found, or the place for inserting, within 421 * the block pointed to by header. 422 * last -- Points right after the last named entry within the block 423 * pointed to by header. 424 * min_offs -- The offset of the first value (values are aligned 425 * towards the end of the block). 426 * end -- Points right after the block pointed to by header. 427 */ 428 429 ea_idebug(inode, "name=%d.%s, value=%p, value_len=%ld", 430 name_index, name, value, (long)value_len); 431 432 if (value == NULL) 433 value_len = 0; 434 if (name == NULL) 435 return -EINVAL; 436 name_len = strlen(name); 437 if (name_len > 255 || value_len > sb->s_blocksize) 438 return -ERANGE; 439 down_write(&EXT2_I(inode)->xattr_sem); 440 if (EXT2_I(inode)->i_file_acl) { 441 /* The inode already has an extended attribute block. */ 442 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 443 error = -EIO; 444 if (!bh) 445 goto cleanup; 446 ea_bdebug(bh, "b_count=%d, refcount=%d", 447 atomic_read(&(bh->b_count)), 448 le32_to_cpu(HDR(bh)->h_refcount)); 449 header = HDR(bh); 450 end = bh->b_data + bh->b_size; 451 if (!ext2_xattr_header_valid(header)) { 452 bad_block: 453 ext2_error(sb, "ext2_xattr_set", 454 "inode %ld: bad block %d", inode->i_ino, 455 EXT2_I(inode)->i_file_acl); 456 error = -EIO; 457 goto cleanup; 458 } 459 /* 460 * Find the named attribute. If not found, 'here' will point 461 * to entry where the new attribute should be inserted to 462 * maintain sorting. 463 */ 464 last = FIRST_ENTRY(bh); 465 while (!IS_LAST_ENTRY(last)) { 466 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize)) 467 goto bad_block; 468 if (last->e_value_size) { 469 size_t offs = le16_to_cpu(last->e_value_offs); 470 if (offs < min_offs) 471 min_offs = offs; 472 } 473 if (not_found > 0) { 474 not_found = ext2_xattr_cmp_entry(name_index, 475 name_len, 476 name, last); 477 if (not_found <= 0) 478 here = last; 479 } 480 last = EXT2_XATTR_NEXT(last); 481 } 482 if (not_found > 0) 483 here = last; 484 485 /* Check whether we have enough space left. */ 486 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 487 } else { 488 /* We will use a new extended attribute block. */ 489 free = sb->s_blocksize - 490 sizeof(struct ext2_xattr_header) - sizeof(__u32); 491 } 492 493 if (not_found) { 494 /* Request to remove a nonexistent attribute? */ 495 error = -ENODATA; 496 if (flags & XATTR_REPLACE) 497 goto cleanup; 498 error = 0; 499 if (value == NULL) 500 goto cleanup; 501 } else { 502 /* Request to create an existing attribute? */ 503 error = -EEXIST; 504 if (flags & XATTR_CREATE) 505 goto cleanup; 506 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size)); 507 free += EXT2_XATTR_LEN(name_len); 508 } 509 error = -ENOSPC; 510 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 511 goto cleanup; 512 513 /* Here we know that we can set the new attribute. */ 514 515 if (header) { 516 /* assert(header == HDR(bh)); */ 517 lock_buffer(bh); 518 if (header->h_refcount == cpu_to_le32(1)) { 519 __u32 hash = le32_to_cpu(header->h_hash); 520 521 ea_bdebug(bh, "modifying in-place"); 522 /* 523 * This must happen under buffer lock for 524 * ext2_xattr_set2() to reliably detect modified block 525 */ 526 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, 527 bh->b_blocknr); 528 529 /* keep the buffer locked while modifying it. */ 530 } else { 531 int offset; 532 533 unlock_buffer(bh); 534 ea_bdebug(bh, "cloning"); 535 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL); 536 error = -ENOMEM; 537 if (header == NULL) 538 goto cleanup; 539 header->h_refcount = cpu_to_le32(1); 540 541 offset = (char *)here - bh->b_data; 542 here = ENTRY((char *)header + offset); 543 offset = (char *)last - bh->b_data; 544 last = ENTRY((char *)header + offset); 545 } 546 } else { 547 /* Allocate a buffer where we construct the new block. */ 548 header = kzalloc(sb->s_blocksize, GFP_KERNEL); 549 error = -ENOMEM; 550 if (header == NULL) 551 goto cleanup; 552 end = (char *)header + sb->s_blocksize; 553 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 554 header->h_blocks = header->h_refcount = cpu_to_le32(1); 555 last = here = ENTRY(header+1); 556 } 557 558 /* Iff we are modifying the block in-place, bh is locked here. */ 559 560 if (not_found) { 561 /* Insert the new name. */ 562 size_t size = EXT2_XATTR_LEN(name_len); 563 size_t rest = (char *)last - (char *)here; 564 memmove((char *)here + size, here, rest); 565 memset(here, 0, size); 566 here->e_name_index = name_index; 567 here->e_name_len = name_len; 568 memcpy(here->e_name, name, name_len); 569 } else { 570 if (here->e_value_size) { 571 char *first_val = (char *)header + min_offs; 572 size_t offs = le16_to_cpu(here->e_value_offs); 573 char *val = (char *)header + offs; 574 size_t size = EXT2_XATTR_SIZE( 575 le32_to_cpu(here->e_value_size)); 576 577 if (size == EXT2_XATTR_SIZE(value_len)) { 578 /* The old and the new value have the same 579 size. Just replace. */ 580 here->e_value_size = cpu_to_le32(value_len); 581 memset(val + size - EXT2_XATTR_PAD, 0, 582 EXT2_XATTR_PAD); /* Clear pad bytes. */ 583 memcpy(val, value, value_len); 584 goto skip_replace; 585 } 586 587 /* Remove the old value. */ 588 memmove(first_val + size, first_val, val - first_val); 589 memset(first_val, 0, size); 590 here->e_value_offs = 0; 591 min_offs += size; 592 593 /* Adjust all value offsets. */ 594 last = ENTRY(header+1); 595 while (!IS_LAST_ENTRY(last)) { 596 size_t o = le16_to_cpu(last->e_value_offs); 597 if (o < offs) 598 last->e_value_offs = 599 cpu_to_le16(o + size); 600 last = EXT2_XATTR_NEXT(last); 601 } 602 } 603 if (value == NULL) { 604 /* Remove the old name. */ 605 size_t size = EXT2_XATTR_LEN(name_len); 606 last = ENTRY((char *)last - size); 607 memmove(here, (char*)here + size, 608 (char*)last - (char*)here); 609 memset(last, 0, size); 610 } 611 } 612 613 if (value != NULL) { 614 /* Insert the new value. */ 615 here->e_value_size = cpu_to_le32(value_len); 616 if (value_len) { 617 size_t size = EXT2_XATTR_SIZE(value_len); 618 char *val = (char *)header + min_offs - size; 619 here->e_value_offs = 620 cpu_to_le16((char *)val - (char *)header); 621 memset(val + size - EXT2_XATTR_PAD, 0, 622 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 623 memcpy(val, value, value_len); 624 } 625 } 626 627 skip_replace: 628 if (IS_LAST_ENTRY(ENTRY(header+1))) { 629 /* This block is now empty. */ 630 if (bh && header == HDR(bh)) 631 unlock_buffer(bh); /* we were modifying in-place. */ 632 error = ext2_xattr_set2(inode, bh, NULL); 633 } else { 634 ext2_xattr_rehash(header, here); 635 if (bh && header == HDR(bh)) 636 unlock_buffer(bh); /* we were modifying in-place. */ 637 error = ext2_xattr_set2(inode, bh, header); 638 } 639 640 cleanup: 641 if (!(bh && header == HDR(bh))) 642 kfree(header); 643 brelse(bh); 644 up_write(&EXT2_I(inode)->xattr_sem); 645 646 return error; 647 } 648 649 /* 650 * Second half of ext2_xattr_set(): Update the file system. 651 */ 652 static int 653 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 654 struct ext2_xattr_header *header) 655 { 656 struct super_block *sb = inode->i_sb; 657 struct buffer_head *new_bh = NULL; 658 int error; 659 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 660 661 if (header) { 662 new_bh = ext2_xattr_cache_find(inode, header); 663 if (new_bh) { 664 /* We found an identical block in the cache. */ 665 if (new_bh == old_bh) { 666 ea_bdebug(new_bh, "keeping this block"); 667 } else { 668 /* The old block is released after updating 669 the inode. */ 670 ea_bdebug(new_bh, "reusing block"); 671 672 error = dquot_alloc_block(inode, 1); 673 if (error) { 674 unlock_buffer(new_bh); 675 goto cleanup; 676 } 677 le32_add_cpu(&HDR(new_bh)->h_refcount, 1); 678 ea_bdebug(new_bh, "refcount now=%d", 679 le32_to_cpu(HDR(new_bh)->h_refcount)); 680 } 681 unlock_buffer(new_bh); 682 } else if (old_bh && header == HDR(old_bh)) { 683 /* Keep this block. No need to lock the block as we 684 don't need to change the reference count. */ 685 new_bh = old_bh; 686 get_bh(new_bh); 687 ext2_xattr_cache_insert(ea_block_cache, new_bh); 688 } else { 689 /* We need to allocate a new block */ 690 ext2_fsblk_t goal = ext2_group_first_block_no(sb, 691 EXT2_I(inode)->i_block_group); 692 int block = ext2_new_block(inode, goal, &error); 693 if (error) 694 goto cleanup; 695 ea_idebug(inode, "creating block %d", block); 696 697 new_bh = sb_getblk(sb, block); 698 if (unlikely(!new_bh)) { 699 ext2_free_blocks(inode, block, 1); 700 mark_inode_dirty(inode); 701 error = -ENOMEM; 702 goto cleanup; 703 } 704 lock_buffer(new_bh); 705 memcpy(new_bh->b_data, header, new_bh->b_size); 706 set_buffer_uptodate(new_bh); 707 unlock_buffer(new_bh); 708 ext2_xattr_cache_insert(ea_block_cache, new_bh); 709 710 ext2_xattr_update_super_block(sb); 711 } 712 mark_buffer_dirty(new_bh); 713 if (IS_SYNC(inode)) { 714 sync_dirty_buffer(new_bh); 715 error = -EIO; 716 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 717 goto cleanup; 718 } 719 } 720 721 /* Update the inode. */ 722 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 723 inode->i_ctime = current_time(inode); 724 if (IS_SYNC(inode)) { 725 error = sync_inode_metadata(inode, 1); 726 /* In case sync failed due to ENOSPC the inode was actually 727 * written (only some dirty data were not) so we just proceed 728 * as if nothing happened and cleanup the unused block */ 729 if (error && error != -ENOSPC) { 730 if (new_bh && new_bh != old_bh) { 731 dquot_free_block_nodirty(inode, 1); 732 mark_inode_dirty(inode); 733 } 734 goto cleanup; 735 } 736 } else 737 mark_inode_dirty(inode); 738 739 error = 0; 740 if (old_bh && old_bh != new_bh) { 741 /* 742 * If there was an old block and we are no longer using it, 743 * release the old block. 744 */ 745 lock_buffer(old_bh); 746 if (HDR(old_bh)->h_refcount == cpu_to_le32(1)) { 747 __u32 hash = le32_to_cpu(HDR(old_bh)->h_hash); 748 749 /* 750 * This must happen under buffer lock for 751 * ext2_xattr_set2() to reliably detect freed block 752 */ 753 mb_cache_entry_delete(ea_block_cache, hash, 754 old_bh->b_blocknr); 755 /* Free the old block. */ 756 ea_bdebug(old_bh, "freeing"); 757 ext2_free_blocks(inode, old_bh->b_blocknr, 1); 758 mark_inode_dirty(inode); 759 /* We let our caller release old_bh, so we 760 * need to duplicate the buffer before. */ 761 get_bh(old_bh); 762 bforget(old_bh); 763 } else { 764 /* Decrement the refcount only. */ 765 le32_add_cpu(&HDR(old_bh)->h_refcount, -1); 766 dquot_free_block_nodirty(inode, 1); 767 mark_inode_dirty(inode); 768 mark_buffer_dirty(old_bh); 769 ea_bdebug(old_bh, "refcount now=%d", 770 le32_to_cpu(HDR(old_bh)->h_refcount)); 771 } 772 unlock_buffer(old_bh); 773 } 774 775 cleanup: 776 brelse(new_bh); 777 778 return error; 779 } 780 781 /* 782 * ext2_xattr_delete_inode() 783 * 784 * Free extended attribute resources associated with this inode. This 785 * is called immediately before an inode is freed. 786 */ 787 void 788 ext2_xattr_delete_inode(struct inode *inode) 789 { 790 struct buffer_head *bh = NULL; 791 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb); 792 793 /* 794 * We are the only ones holding inode reference. The xattr_sem should 795 * better be unlocked! We could as well just not acquire xattr_sem at 796 * all but this makes the code more futureproof. OTOH we need trylock 797 * here to avoid false-positive warning from lockdep about reclaim 798 * circular dependency. 799 */ 800 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem))) 801 return; 802 if (!EXT2_I(inode)->i_file_acl) 803 goto cleanup; 804 805 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) { 806 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 807 "inode %ld: xattr block %d is out of data blocks range", 808 inode->i_ino, EXT2_I(inode)->i_file_acl); 809 goto cleanup; 810 } 811 812 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 813 if (!bh) { 814 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 815 "inode %ld: block %d read error", inode->i_ino, 816 EXT2_I(inode)->i_file_acl); 817 goto cleanup; 818 } 819 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 820 if (!ext2_xattr_header_valid(HDR(bh))) { 821 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 822 "inode %ld: bad block %d", inode->i_ino, 823 EXT2_I(inode)->i_file_acl); 824 goto cleanup; 825 } 826 lock_buffer(bh); 827 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 828 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 829 830 /* 831 * This must happen under buffer lock for ext2_xattr_set2() to 832 * reliably detect freed block 833 */ 834 mb_cache_entry_delete(EA_BLOCK_CACHE(inode), hash, 835 bh->b_blocknr); 836 ext2_free_blocks(inode, EXT2_I(inode)->i_file_acl, 1); 837 get_bh(bh); 838 bforget(bh); 839 unlock_buffer(bh); 840 } else { 841 le32_add_cpu(&HDR(bh)->h_refcount, -1); 842 ea_bdebug(bh, "refcount now=%d", 843 le32_to_cpu(HDR(bh)->h_refcount)); 844 unlock_buffer(bh); 845 mark_buffer_dirty(bh); 846 if (IS_SYNC(inode)) 847 sync_dirty_buffer(bh); 848 dquot_free_block_nodirty(inode, 1); 849 } 850 EXT2_I(inode)->i_file_acl = 0; 851 852 cleanup: 853 brelse(bh); 854 up_write(&EXT2_I(inode)->xattr_sem); 855 } 856 857 /* 858 * ext2_xattr_cache_insert() 859 * 860 * Create a new entry in the extended attribute cache, and insert 861 * it unless such an entry is already in the cache. 862 * 863 * Returns 0, or a negative error number on failure. 864 */ 865 static int 866 ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) 867 { 868 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 869 int error; 870 871 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 872 true); 873 if (error) { 874 if (error == -EBUSY) { 875 ea_bdebug(bh, "already in cache"); 876 error = 0; 877 } 878 } else 879 ea_bdebug(bh, "inserting [%x]", (int)hash); 880 return error; 881 } 882 883 /* 884 * ext2_xattr_cmp() 885 * 886 * Compare two extended attribute blocks for equality. 887 * 888 * Returns 0 if the blocks are equal, 1 if they differ, and 889 * a negative error number on errors. 890 */ 891 static int 892 ext2_xattr_cmp(struct ext2_xattr_header *header1, 893 struct ext2_xattr_header *header2) 894 { 895 struct ext2_xattr_entry *entry1, *entry2; 896 897 entry1 = ENTRY(header1+1); 898 entry2 = ENTRY(header2+1); 899 while (!IS_LAST_ENTRY(entry1)) { 900 if (IS_LAST_ENTRY(entry2)) 901 return 1; 902 if (entry1->e_hash != entry2->e_hash || 903 entry1->e_name_index != entry2->e_name_index || 904 entry1->e_name_len != entry2->e_name_len || 905 entry1->e_value_size != entry2->e_value_size || 906 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 907 return 1; 908 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 909 return -EIO; 910 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 911 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 912 le32_to_cpu(entry1->e_value_size))) 913 return 1; 914 915 entry1 = EXT2_XATTR_NEXT(entry1); 916 entry2 = EXT2_XATTR_NEXT(entry2); 917 } 918 if (!IS_LAST_ENTRY(entry2)) 919 return 1; 920 return 0; 921 } 922 923 /* 924 * ext2_xattr_cache_find() 925 * 926 * Find an identical extended attribute block. 927 * 928 * Returns a locked buffer head to the block found, or NULL if such 929 * a block was not found or an error occurred. 930 */ 931 static struct buffer_head * 932 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 933 { 934 __u32 hash = le32_to_cpu(header->h_hash); 935 struct mb_cache_entry *ce; 936 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 937 938 if (!header->h_hash) 939 return NULL; /* never share */ 940 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 941 again: 942 ce = mb_cache_entry_find_first(ea_block_cache, hash); 943 while (ce) { 944 struct buffer_head *bh; 945 946 bh = sb_bread(inode->i_sb, ce->e_value); 947 if (!bh) { 948 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 949 "inode %ld: block %ld read error", 950 inode->i_ino, (unsigned long) ce->e_value); 951 } else { 952 lock_buffer(bh); 953 /* 954 * We have to be careful about races with freeing or 955 * rehashing of xattr block. Once we hold buffer lock 956 * xattr block's state is stable so we can check 957 * whether the block got freed / rehashed or not. 958 * Since we unhash mbcache entry under buffer lock when 959 * freeing / rehashing xattr block, checking whether 960 * entry is still hashed is reliable. 961 */ 962 if (hlist_bl_unhashed(&ce->e_hash_list)) { 963 mb_cache_entry_put(ea_block_cache, ce); 964 unlock_buffer(bh); 965 brelse(bh); 966 goto again; 967 } else if (le32_to_cpu(HDR(bh)->h_refcount) > 968 EXT2_XATTR_REFCOUNT_MAX) { 969 ea_idebug(inode, "block %ld refcount %d>%d", 970 (unsigned long) ce->e_value, 971 le32_to_cpu(HDR(bh)->h_refcount), 972 EXT2_XATTR_REFCOUNT_MAX); 973 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 974 ea_bdebug(bh, "b_count=%d", 975 atomic_read(&(bh->b_count))); 976 mb_cache_entry_touch(ea_block_cache, ce); 977 mb_cache_entry_put(ea_block_cache, ce); 978 return bh; 979 } 980 unlock_buffer(bh); 981 brelse(bh); 982 } 983 ce = mb_cache_entry_find_next(ea_block_cache, ce); 984 } 985 return NULL; 986 } 987 988 #define NAME_HASH_SHIFT 5 989 #define VALUE_HASH_SHIFT 16 990 991 /* 992 * ext2_xattr_hash_entry() 993 * 994 * Compute the hash of an extended attribute. 995 */ 996 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 997 struct ext2_xattr_entry *entry) 998 { 999 __u32 hash = 0; 1000 char *name = entry->e_name; 1001 int n; 1002 1003 for (n=0; n < entry->e_name_len; n++) { 1004 hash = (hash << NAME_HASH_SHIFT) ^ 1005 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 1006 *name++; 1007 } 1008 1009 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 1010 __le32 *value = (__le32 *)((char *)header + 1011 le16_to_cpu(entry->e_value_offs)); 1012 for (n = (le32_to_cpu(entry->e_value_size) + 1013 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 1014 hash = (hash << VALUE_HASH_SHIFT) ^ 1015 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 1016 le32_to_cpu(*value++); 1017 } 1018 } 1019 entry->e_hash = cpu_to_le32(hash); 1020 } 1021 1022 #undef NAME_HASH_SHIFT 1023 #undef VALUE_HASH_SHIFT 1024 1025 #define BLOCK_HASH_SHIFT 16 1026 1027 /* 1028 * ext2_xattr_rehash() 1029 * 1030 * Re-compute the extended attribute hash value after an entry has changed. 1031 */ 1032 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 1033 struct ext2_xattr_entry *entry) 1034 { 1035 struct ext2_xattr_entry *here; 1036 __u32 hash = 0; 1037 1038 ext2_xattr_hash_entry(header, entry); 1039 here = ENTRY(header+1); 1040 while (!IS_LAST_ENTRY(here)) { 1041 if (!here->e_hash) { 1042 /* Block is not shared if an entry's hash value == 0 */ 1043 hash = 0; 1044 break; 1045 } 1046 hash = (hash << BLOCK_HASH_SHIFT) ^ 1047 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1048 le32_to_cpu(here->e_hash); 1049 here = EXT2_XATTR_NEXT(here); 1050 } 1051 header->h_hash = cpu_to_le32(hash); 1052 } 1053 1054 #undef BLOCK_HASH_SHIFT 1055 1056 #define HASH_BUCKET_BITS 10 1057 1058 struct mb_cache *ext2_xattr_create_cache(void) 1059 { 1060 return mb_cache_create(HASH_BUCKET_BITS); 1061 } 1062 1063 void ext2_xattr_destroy_cache(struct mb_cache *cache) 1064 { 1065 if (cache) 1066 mb_cache_destroy(cache); 1067 } 1068