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/printk.h> 60 #include <linux/slab.h> 61 #include <linux/mbcache.h> 62 #include <linux/quotaops.h> 63 #include <linux/rwsem.h> 64 #include <linux/security.h> 65 #include "ext2.h" 66 #include "xattr.h" 67 #include "acl.h" 68 69 #define HDR(bh) ((struct ext2_xattr_header *)((bh)->b_data)) 70 #define ENTRY(ptr) ((struct ext2_xattr_entry *)(ptr)) 71 #define FIRST_ENTRY(bh) ENTRY(HDR(bh)+1) 72 #define IS_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0) 73 74 #ifdef EXT2_XATTR_DEBUG 75 # define ea_idebug(inode, f...) do { \ 76 printk(KERN_DEBUG "inode %s:%ld: ", \ 77 inode->i_sb->s_id, inode->i_ino); \ 78 printk(f); \ 79 printk("\n"); \ 80 } while (0) 81 # define ea_bdebug(bh, f...) do { \ 82 printk(KERN_DEBUG "block %pg:%lu: ", \ 83 bh->b_bdev, (unsigned long) bh->b_blocknr); \ 84 printk(f); \ 85 printk("\n"); \ 86 } while (0) 87 #else 88 # define ea_idebug(inode, f...) no_printk(f) 89 # define ea_bdebug(bh, f...) no_printk(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 mb_cache *, 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 const struct xattr_handler *ext2_xattr_handler_map[] = { 102 [EXT2_XATTR_INDEX_USER] = &ext2_xattr_user_handler, 103 #ifdef CONFIG_EXT2_FS_POSIX_ACL 104 [EXT2_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler, 105 [EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT] = &posix_acl_default_xattr_handler, 106 #endif 107 [EXT2_XATTR_INDEX_TRUSTED] = &ext2_xattr_trusted_handler, 108 #ifdef CONFIG_EXT2_FS_SECURITY 109 [EXT2_XATTR_INDEX_SECURITY] = &ext2_xattr_security_handler, 110 #endif 111 }; 112 113 const struct xattr_handler *ext2_xattr_handlers[] = { 114 &ext2_xattr_user_handler, 115 &ext2_xattr_trusted_handler, 116 #ifdef CONFIG_EXT2_FS_SECURITY 117 &ext2_xattr_security_handler, 118 #endif 119 NULL 120 }; 121 122 #define EA_BLOCK_CACHE(inode) (EXT2_SB(inode->i_sb)->s_ea_block_cache) 123 124 static inline const char *ext2_xattr_prefix(int name_index, 125 struct dentry *dentry) 126 { 127 const struct xattr_handler *handler = NULL; 128 129 if (name_index > 0 && name_index < ARRAY_SIZE(ext2_xattr_handler_map)) 130 handler = ext2_xattr_handler_map[name_index]; 131 132 if (!xattr_handler_can_list(handler, dentry)) 133 return NULL; 134 135 return xattr_prefix(handler); 136 } 137 138 static bool 139 ext2_xattr_header_valid(struct ext2_xattr_header *header) 140 { 141 if (header->h_magic != cpu_to_le32(EXT2_XATTR_MAGIC) || 142 header->h_blocks != cpu_to_le32(1)) 143 return false; 144 145 return true; 146 } 147 148 static bool 149 ext2_xattr_entry_valid(struct ext2_xattr_entry *entry, 150 char *end, size_t end_offs) 151 { 152 struct ext2_xattr_entry *next; 153 size_t size; 154 155 next = EXT2_XATTR_NEXT(entry); 156 if ((char *)next >= end) 157 return false; 158 159 if (entry->e_value_block != 0) 160 return false; 161 162 size = le32_to_cpu(entry->e_value_size); 163 if (size > end_offs || 164 le16_to_cpu(entry->e_value_offs) + size > end_offs) 165 return false; 166 167 return true; 168 } 169 170 static int 171 ext2_xattr_cmp_entry(int name_index, size_t name_len, const char *name, 172 struct ext2_xattr_entry *entry) 173 { 174 int cmp; 175 176 cmp = name_index - entry->e_name_index; 177 if (!cmp) 178 cmp = name_len - entry->e_name_len; 179 if (!cmp) 180 cmp = memcmp(name, entry->e_name, name_len); 181 182 return cmp; 183 } 184 185 /* 186 * ext2_xattr_get() 187 * 188 * Copy an extended attribute into the buffer 189 * provided, or compute the buffer size required. 190 * Buffer is NULL to compute the size of the buffer required. 191 * 192 * Returns a negative error number on failure, or the number of bytes 193 * used / required on success. 194 */ 195 int 196 ext2_xattr_get(struct inode *inode, int name_index, const char *name, 197 void *buffer, size_t buffer_size) 198 { 199 struct buffer_head *bh = NULL; 200 struct ext2_xattr_entry *entry; 201 size_t name_len, size; 202 char *end; 203 int error, not_found; 204 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 205 206 ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld", 207 name_index, name, buffer, (long)buffer_size); 208 209 if (name == NULL) 210 return -EINVAL; 211 name_len = strlen(name); 212 if (name_len > 255) 213 return -ERANGE; 214 215 down_read(&EXT2_I(inode)->xattr_sem); 216 error = -ENODATA; 217 if (!EXT2_I(inode)->i_file_acl) 218 goto cleanup; 219 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 220 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 221 error = -EIO; 222 if (!bh) 223 goto cleanup; 224 ea_bdebug(bh, "b_count=%d, refcount=%d", 225 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 226 end = bh->b_data + bh->b_size; 227 if (!ext2_xattr_header_valid(HDR(bh))) { 228 bad_block: 229 ext2_error(inode->i_sb, "ext2_xattr_get", 230 "inode %ld: bad block %d", inode->i_ino, 231 EXT2_I(inode)->i_file_acl); 232 error = -EIO; 233 goto cleanup; 234 } 235 236 /* find named attribute */ 237 entry = FIRST_ENTRY(bh); 238 while (!IS_LAST_ENTRY(entry)) { 239 if (!ext2_xattr_entry_valid(entry, end, 240 inode->i_sb->s_blocksize)) 241 goto bad_block; 242 243 not_found = ext2_xattr_cmp_entry(name_index, name_len, name, 244 entry); 245 if (!not_found) 246 goto found; 247 if (not_found < 0) 248 break; 249 250 entry = EXT2_XATTR_NEXT(entry); 251 } 252 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 253 ea_idebug(inode, "cache insert failed"); 254 error = -ENODATA; 255 goto cleanup; 256 found: 257 size = le32_to_cpu(entry->e_value_size); 258 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 259 ea_idebug(inode, "cache insert failed"); 260 if (buffer) { 261 error = -ERANGE; 262 if (size > buffer_size) 263 goto cleanup; 264 /* return value of attribute */ 265 memcpy(buffer, bh->b_data + le16_to_cpu(entry->e_value_offs), 266 size); 267 } 268 error = size; 269 270 cleanup: 271 brelse(bh); 272 up_read(&EXT2_I(inode)->xattr_sem); 273 274 return error; 275 } 276 277 /* 278 * ext2_xattr_list() 279 * 280 * Copy a list of attribute names into the buffer 281 * provided, or compute the buffer size required. 282 * Buffer is NULL to compute the size of the buffer required. 283 * 284 * Returns a negative error number on failure, or the number of bytes 285 * used / required on success. 286 */ 287 static int 288 ext2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size) 289 { 290 struct inode *inode = d_inode(dentry); 291 struct buffer_head *bh = NULL; 292 struct ext2_xattr_entry *entry; 293 char *end; 294 size_t rest = buffer_size; 295 int error; 296 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 297 298 ea_idebug(inode, "buffer=%p, buffer_size=%ld", 299 buffer, (long)buffer_size); 300 301 down_read(&EXT2_I(inode)->xattr_sem); 302 error = 0; 303 if (!EXT2_I(inode)->i_file_acl) 304 goto cleanup; 305 ea_idebug(inode, "reading block %d", EXT2_I(inode)->i_file_acl); 306 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 307 error = -EIO; 308 if (!bh) 309 goto cleanup; 310 ea_bdebug(bh, "b_count=%d, refcount=%d", 311 atomic_read(&(bh->b_count)), le32_to_cpu(HDR(bh)->h_refcount)); 312 end = bh->b_data + bh->b_size; 313 if (!ext2_xattr_header_valid(HDR(bh))) { 314 bad_block: 315 ext2_error(inode->i_sb, "ext2_xattr_list", 316 "inode %ld: bad block %d", inode->i_ino, 317 EXT2_I(inode)->i_file_acl); 318 error = -EIO; 319 goto cleanup; 320 } 321 322 /* check the on-disk data structure */ 323 entry = FIRST_ENTRY(bh); 324 while (!IS_LAST_ENTRY(entry)) { 325 if (!ext2_xattr_entry_valid(entry, end, 326 inode->i_sb->s_blocksize)) 327 goto bad_block; 328 entry = EXT2_XATTR_NEXT(entry); 329 } 330 if (ext2_xattr_cache_insert(ea_block_cache, bh)) 331 ea_idebug(inode, "cache insert failed"); 332 333 /* list the attribute names */ 334 for (entry = FIRST_ENTRY(bh); !IS_LAST_ENTRY(entry); 335 entry = EXT2_XATTR_NEXT(entry)) { 336 const char *prefix; 337 338 prefix = ext2_xattr_prefix(entry->e_name_index, dentry); 339 if (prefix) { 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 error = dquot_initialize(inode); 440 if (error) 441 return error; 442 down_write(&EXT2_I(inode)->xattr_sem); 443 if (EXT2_I(inode)->i_file_acl) { 444 /* The inode already has an extended attribute block. */ 445 bh = sb_bread(sb, EXT2_I(inode)->i_file_acl); 446 error = -EIO; 447 if (!bh) 448 goto cleanup; 449 ea_bdebug(bh, "b_count=%d, refcount=%d", 450 atomic_read(&(bh->b_count)), 451 le32_to_cpu(HDR(bh)->h_refcount)); 452 header = HDR(bh); 453 end = bh->b_data + bh->b_size; 454 if (!ext2_xattr_header_valid(header)) { 455 bad_block: 456 ext2_error(sb, "ext2_xattr_set", 457 "inode %ld: bad block %d", inode->i_ino, 458 EXT2_I(inode)->i_file_acl); 459 error = -EIO; 460 goto cleanup; 461 } 462 /* 463 * Find the named attribute. If not found, 'here' will point 464 * to entry where the new attribute should be inserted to 465 * maintain sorting. 466 */ 467 last = FIRST_ENTRY(bh); 468 while (!IS_LAST_ENTRY(last)) { 469 if (!ext2_xattr_entry_valid(last, end, sb->s_blocksize)) 470 goto bad_block; 471 if (last->e_value_size) { 472 size_t offs = le16_to_cpu(last->e_value_offs); 473 if (offs < min_offs) 474 min_offs = offs; 475 } 476 if (not_found > 0) { 477 not_found = ext2_xattr_cmp_entry(name_index, 478 name_len, 479 name, last); 480 if (not_found <= 0) 481 here = last; 482 } 483 last = EXT2_XATTR_NEXT(last); 484 } 485 if (not_found > 0) 486 here = last; 487 488 /* Check whether we have enough space left. */ 489 free = min_offs - ((char*)last - (char*)header) - sizeof(__u32); 490 } else { 491 /* We will use a new extended attribute block. */ 492 free = sb->s_blocksize - 493 sizeof(struct ext2_xattr_header) - sizeof(__u32); 494 } 495 496 if (not_found) { 497 /* Request to remove a nonexistent attribute? */ 498 error = -ENODATA; 499 if (flags & XATTR_REPLACE) 500 goto cleanup; 501 error = 0; 502 if (value == NULL) 503 goto cleanup; 504 } else { 505 /* Request to create an existing attribute? */ 506 error = -EEXIST; 507 if (flags & XATTR_CREATE) 508 goto cleanup; 509 free += EXT2_XATTR_SIZE(le32_to_cpu(here->e_value_size)); 510 free += EXT2_XATTR_LEN(name_len); 511 } 512 error = -ENOSPC; 513 if (free < EXT2_XATTR_LEN(name_len) + EXT2_XATTR_SIZE(value_len)) 514 goto cleanup; 515 516 /* Here we know that we can set the new attribute. */ 517 518 if (header) { 519 int offset; 520 521 lock_buffer(bh); 522 if (header->h_refcount == cpu_to_le32(1)) { 523 __u32 hash = le32_to_cpu(header->h_hash); 524 struct mb_cache_entry *oe; 525 526 oe = mb_cache_entry_delete_or_get(EA_BLOCK_CACHE(inode), 527 hash, bh->b_blocknr); 528 if (!oe) { 529 ea_bdebug(bh, "modifying in-place"); 530 goto update_block; 531 } 532 /* 533 * Someone is trying to reuse the block, leave it alone 534 */ 535 mb_cache_entry_put(EA_BLOCK_CACHE(inode), oe); 536 } 537 unlock_buffer(bh); 538 ea_bdebug(bh, "cloning"); 539 header = kmemdup(HDR(bh), bh->b_size, GFP_KERNEL); 540 error = -ENOMEM; 541 if (header == NULL) 542 goto cleanup; 543 header->h_refcount = cpu_to_le32(1); 544 545 offset = (char *)here - bh->b_data; 546 here = ENTRY((char *)header + offset); 547 offset = (char *)last - bh->b_data; 548 last = ENTRY((char *)header + offset); 549 } else { 550 /* Allocate a buffer where we construct the new block. */ 551 header = kzalloc(sb->s_blocksize, GFP_KERNEL); 552 error = -ENOMEM; 553 if (header == NULL) 554 goto cleanup; 555 end = (char *)header + sb->s_blocksize; 556 header->h_magic = cpu_to_le32(EXT2_XATTR_MAGIC); 557 header->h_blocks = header->h_refcount = cpu_to_le32(1); 558 last = here = ENTRY(header+1); 559 } 560 561 update_block: 562 /* Iff we are modifying the block in-place, bh is locked here. */ 563 564 if (not_found) { 565 /* Insert the new name. */ 566 size_t size = EXT2_XATTR_LEN(name_len); 567 size_t rest = (char *)last - (char *)here; 568 memmove((char *)here + size, here, rest); 569 memset(here, 0, size); 570 here->e_name_index = name_index; 571 here->e_name_len = name_len; 572 memcpy(here->e_name, name, name_len); 573 } else { 574 if (here->e_value_size) { 575 char *first_val = (char *)header + min_offs; 576 size_t offs = le16_to_cpu(here->e_value_offs); 577 char *val = (char *)header + offs; 578 size_t size = EXT2_XATTR_SIZE( 579 le32_to_cpu(here->e_value_size)); 580 581 if (size == EXT2_XATTR_SIZE(value_len)) { 582 /* The old and the new value have the same 583 size. Just replace. */ 584 here->e_value_size = cpu_to_le32(value_len); 585 memset(val + size - EXT2_XATTR_PAD, 0, 586 EXT2_XATTR_PAD); /* Clear pad bytes. */ 587 memcpy(val, value, value_len); 588 goto skip_replace; 589 } 590 591 /* Remove the old value. */ 592 memmove(first_val + size, first_val, val - first_val); 593 memset(first_val, 0, size); 594 min_offs += size; 595 596 /* Adjust all value offsets. */ 597 last = ENTRY(header+1); 598 while (!IS_LAST_ENTRY(last)) { 599 size_t o = le16_to_cpu(last->e_value_offs); 600 if (o < offs) 601 last->e_value_offs = 602 cpu_to_le16(o + size); 603 last = EXT2_XATTR_NEXT(last); 604 } 605 606 here->e_value_offs = 0; 607 } 608 if (value == NULL) { 609 /* Remove the old name. */ 610 size_t size = EXT2_XATTR_LEN(name_len); 611 last = ENTRY((char *)last - size); 612 memmove(here, (char*)here + size, 613 (char*)last - (char*)here); 614 memset(last, 0, size); 615 } 616 } 617 618 if (value != NULL) { 619 /* Insert the new value. */ 620 here->e_value_size = cpu_to_le32(value_len); 621 if (value_len) { 622 size_t size = EXT2_XATTR_SIZE(value_len); 623 char *val = (char *)header + min_offs - size; 624 here->e_value_offs = 625 cpu_to_le16((char *)val - (char *)header); 626 memset(val + size - EXT2_XATTR_PAD, 0, 627 EXT2_XATTR_PAD); /* Clear the pad bytes. */ 628 memcpy(val, value, value_len); 629 } 630 } 631 632 skip_replace: 633 if (IS_LAST_ENTRY(ENTRY(header+1))) { 634 /* This block is now empty. */ 635 if (bh && header == HDR(bh)) 636 unlock_buffer(bh); /* we were modifying in-place. */ 637 error = ext2_xattr_set2(inode, bh, NULL); 638 } else { 639 ext2_xattr_rehash(header, here); 640 if (bh && header == HDR(bh)) 641 unlock_buffer(bh); /* we were modifying in-place. */ 642 error = ext2_xattr_set2(inode, bh, header); 643 } 644 645 cleanup: 646 if (!(bh && header == HDR(bh))) 647 kfree(header); 648 brelse(bh); 649 up_write(&EXT2_I(inode)->xattr_sem); 650 651 return error; 652 } 653 654 static void ext2_xattr_release_block(struct inode *inode, 655 struct buffer_head *bh) 656 { 657 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 658 659 retry_ref: 660 lock_buffer(bh); 661 if (HDR(bh)->h_refcount == cpu_to_le32(1)) { 662 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 663 struct mb_cache_entry *oe; 664 665 /* 666 * This must happen under buffer lock to properly 667 * serialize with ext2_xattr_set() reusing the block. 668 */ 669 oe = mb_cache_entry_delete_or_get(ea_block_cache, hash, 670 bh->b_blocknr); 671 if (oe) { 672 /* 673 * Someone is trying to reuse the block. Wait 674 * and retry. 675 */ 676 unlock_buffer(bh); 677 mb_cache_entry_wait_unused(oe); 678 mb_cache_entry_put(ea_block_cache, oe); 679 goto retry_ref; 680 } 681 682 /* Free the old block. */ 683 ea_bdebug(bh, "freeing"); 684 ext2_free_blocks(inode, bh->b_blocknr, 1); 685 /* We let our caller release bh, so we 686 * need to duplicate the buffer before. */ 687 get_bh(bh); 688 bforget(bh); 689 unlock_buffer(bh); 690 } else { 691 /* Decrement the refcount only. */ 692 le32_add_cpu(&HDR(bh)->h_refcount, -1); 693 dquot_free_block(inode, 1); 694 mark_buffer_dirty(bh); 695 unlock_buffer(bh); 696 ea_bdebug(bh, "refcount now=%d", 697 le32_to_cpu(HDR(bh)->h_refcount)); 698 if (IS_SYNC(inode)) 699 sync_dirty_buffer(bh); 700 } 701 } 702 703 /* 704 * Second half of ext2_xattr_set(): Update the file system. 705 */ 706 static int 707 ext2_xattr_set2(struct inode *inode, struct buffer_head *old_bh, 708 struct ext2_xattr_header *header) 709 { 710 struct super_block *sb = inode->i_sb; 711 struct buffer_head *new_bh = NULL; 712 int error; 713 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 714 715 if (header) { 716 new_bh = ext2_xattr_cache_find(inode, header); 717 if (new_bh) { 718 /* We found an identical block in the cache. */ 719 if (new_bh == old_bh) { 720 ea_bdebug(new_bh, "keeping this block"); 721 } else { 722 /* The old block is released after updating 723 the inode. */ 724 ea_bdebug(new_bh, "reusing block"); 725 726 error = dquot_alloc_block(inode, 1); 727 if (error) { 728 unlock_buffer(new_bh); 729 goto cleanup; 730 } 731 le32_add_cpu(&HDR(new_bh)->h_refcount, 1); 732 ea_bdebug(new_bh, "refcount now=%d", 733 le32_to_cpu(HDR(new_bh)->h_refcount)); 734 } 735 unlock_buffer(new_bh); 736 } else if (old_bh && header == HDR(old_bh)) { 737 /* Keep this block. No need to lock the block as we 738 don't need to change the reference count. */ 739 new_bh = old_bh; 740 get_bh(new_bh); 741 ext2_xattr_cache_insert(ea_block_cache, new_bh); 742 } else { 743 /* We need to allocate a new block */ 744 ext2_fsblk_t goal = ext2_group_first_block_no(sb, 745 EXT2_I(inode)->i_block_group); 746 int block = ext2_new_block(inode, goal, &error); 747 if (error) 748 goto cleanup; 749 ea_idebug(inode, "creating block %d", block); 750 751 new_bh = sb_getblk(sb, block); 752 if (unlikely(!new_bh)) { 753 ext2_free_blocks(inode, block, 1); 754 mark_inode_dirty(inode); 755 error = -ENOMEM; 756 goto cleanup; 757 } 758 lock_buffer(new_bh); 759 memcpy(new_bh->b_data, header, new_bh->b_size); 760 set_buffer_uptodate(new_bh); 761 unlock_buffer(new_bh); 762 ext2_xattr_cache_insert(ea_block_cache, new_bh); 763 764 ext2_xattr_update_super_block(sb); 765 } 766 mark_buffer_dirty(new_bh); 767 if (IS_SYNC(inode)) { 768 sync_dirty_buffer(new_bh); 769 error = -EIO; 770 if (buffer_req(new_bh) && !buffer_uptodate(new_bh)) 771 goto cleanup; 772 } 773 } 774 775 /* Update the inode. */ 776 EXT2_I(inode)->i_file_acl = new_bh ? new_bh->b_blocknr : 0; 777 inode->i_ctime = current_time(inode); 778 if (IS_SYNC(inode)) { 779 error = sync_inode_metadata(inode, 1); 780 /* In case sync failed due to ENOSPC the inode was actually 781 * written (only some dirty data were not) so we just proceed 782 * as if nothing happened and cleanup the unused block */ 783 if (error && error != -ENOSPC) { 784 if (new_bh && new_bh != old_bh) { 785 dquot_free_block_nodirty(inode, 1); 786 mark_inode_dirty(inode); 787 } 788 goto cleanup; 789 } 790 } else 791 mark_inode_dirty(inode); 792 793 error = 0; 794 if (old_bh && old_bh != new_bh) { 795 /* 796 * If there was an old block and we are no longer using it, 797 * release the old block. 798 */ 799 ext2_xattr_release_block(inode, old_bh); 800 } 801 802 cleanup: 803 brelse(new_bh); 804 805 return error; 806 } 807 808 /* 809 * ext2_xattr_delete_inode() 810 * 811 * Free extended attribute resources associated with this inode. This 812 * is called immediately before an inode is freed. 813 */ 814 void 815 ext2_xattr_delete_inode(struct inode *inode) 816 { 817 struct buffer_head *bh = NULL; 818 struct ext2_sb_info *sbi = EXT2_SB(inode->i_sb); 819 820 /* 821 * We are the only ones holding inode reference. The xattr_sem should 822 * better be unlocked! We could as well just not acquire xattr_sem at 823 * all but this makes the code more futureproof. OTOH we need trylock 824 * here to avoid false-positive warning from lockdep about reclaim 825 * circular dependency. 826 */ 827 if (WARN_ON_ONCE(!down_write_trylock(&EXT2_I(inode)->xattr_sem))) 828 return; 829 if (!EXT2_I(inode)->i_file_acl) 830 goto cleanup; 831 832 if (!ext2_data_block_valid(sbi, EXT2_I(inode)->i_file_acl, 1)) { 833 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 834 "inode %ld: xattr block %d is out of data blocks range", 835 inode->i_ino, EXT2_I(inode)->i_file_acl); 836 goto cleanup; 837 } 838 839 bh = sb_bread(inode->i_sb, EXT2_I(inode)->i_file_acl); 840 if (!bh) { 841 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 842 "inode %ld: block %d read error", inode->i_ino, 843 EXT2_I(inode)->i_file_acl); 844 goto cleanup; 845 } 846 ea_bdebug(bh, "b_count=%d", atomic_read(&(bh->b_count))); 847 if (!ext2_xattr_header_valid(HDR(bh))) { 848 ext2_error(inode->i_sb, "ext2_xattr_delete_inode", 849 "inode %ld: bad block %d", inode->i_ino, 850 EXT2_I(inode)->i_file_acl); 851 goto cleanup; 852 } 853 ext2_xattr_release_block(inode, bh); 854 EXT2_I(inode)->i_file_acl = 0; 855 856 cleanup: 857 brelse(bh); 858 up_write(&EXT2_I(inode)->xattr_sem); 859 } 860 861 /* 862 * ext2_xattr_cache_insert() 863 * 864 * Create a new entry in the extended attribute cache, and insert 865 * it unless such an entry is already in the cache. 866 * 867 * Returns 0, or a negative error number on failure. 868 */ 869 static int 870 ext2_xattr_cache_insert(struct mb_cache *cache, struct buffer_head *bh) 871 { 872 __u32 hash = le32_to_cpu(HDR(bh)->h_hash); 873 int error; 874 875 error = mb_cache_entry_create(cache, GFP_NOFS, hash, bh->b_blocknr, 876 true); 877 if (error) { 878 if (error == -EBUSY) { 879 ea_bdebug(bh, "already in cache"); 880 error = 0; 881 } 882 } else 883 ea_bdebug(bh, "inserting [%x]", (int)hash); 884 return error; 885 } 886 887 /* 888 * ext2_xattr_cmp() 889 * 890 * Compare two extended attribute blocks for equality. 891 * 892 * Returns 0 if the blocks are equal, 1 if they differ, and 893 * a negative error number on errors. 894 */ 895 static int 896 ext2_xattr_cmp(struct ext2_xattr_header *header1, 897 struct ext2_xattr_header *header2) 898 { 899 struct ext2_xattr_entry *entry1, *entry2; 900 901 entry1 = ENTRY(header1+1); 902 entry2 = ENTRY(header2+1); 903 while (!IS_LAST_ENTRY(entry1)) { 904 if (IS_LAST_ENTRY(entry2)) 905 return 1; 906 if (entry1->e_hash != entry2->e_hash || 907 entry1->e_name_index != entry2->e_name_index || 908 entry1->e_name_len != entry2->e_name_len || 909 entry1->e_value_size != entry2->e_value_size || 910 memcmp(entry1->e_name, entry2->e_name, entry1->e_name_len)) 911 return 1; 912 if (entry1->e_value_block != 0 || entry2->e_value_block != 0) 913 return -EIO; 914 if (memcmp((char *)header1 + le16_to_cpu(entry1->e_value_offs), 915 (char *)header2 + le16_to_cpu(entry2->e_value_offs), 916 le32_to_cpu(entry1->e_value_size))) 917 return 1; 918 919 entry1 = EXT2_XATTR_NEXT(entry1); 920 entry2 = EXT2_XATTR_NEXT(entry2); 921 } 922 if (!IS_LAST_ENTRY(entry2)) 923 return 1; 924 return 0; 925 } 926 927 /* 928 * ext2_xattr_cache_find() 929 * 930 * Find an identical extended attribute block. 931 * 932 * Returns a locked buffer head to the block found, or NULL if such 933 * a block was not found or an error occurred. 934 */ 935 static struct buffer_head * 936 ext2_xattr_cache_find(struct inode *inode, struct ext2_xattr_header *header) 937 { 938 __u32 hash = le32_to_cpu(header->h_hash); 939 struct mb_cache_entry *ce; 940 struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode); 941 942 if (!header->h_hash) 943 return NULL; /* never share */ 944 ea_idebug(inode, "looking for cached blocks [%x]", (int)hash); 945 946 ce = mb_cache_entry_find_first(ea_block_cache, hash); 947 while (ce) { 948 struct buffer_head *bh; 949 950 bh = sb_bread(inode->i_sb, ce->e_value); 951 if (!bh) { 952 ext2_error(inode->i_sb, "ext2_xattr_cache_find", 953 "inode %ld: block %ld read error", 954 inode->i_ino, (unsigned long) ce->e_value); 955 } else { 956 lock_buffer(bh); 957 if (le32_to_cpu(HDR(bh)->h_refcount) > 958 EXT2_XATTR_REFCOUNT_MAX) { 959 ea_idebug(inode, "block %ld refcount %d>%d", 960 (unsigned long) ce->e_value, 961 le32_to_cpu(HDR(bh)->h_refcount), 962 EXT2_XATTR_REFCOUNT_MAX); 963 } else if (!ext2_xattr_cmp(header, HDR(bh))) { 964 ea_bdebug(bh, "b_count=%d", 965 atomic_read(&(bh->b_count))); 966 mb_cache_entry_touch(ea_block_cache, ce); 967 mb_cache_entry_put(ea_block_cache, ce); 968 return bh; 969 } 970 unlock_buffer(bh); 971 brelse(bh); 972 } 973 ce = mb_cache_entry_find_next(ea_block_cache, ce); 974 } 975 return NULL; 976 } 977 978 #define NAME_HASH_SHIFT 5 979 #define VALUE_HASH_SHIFT 16 980 981 /* 982 * ext2_xattr_hash_entry() 983 * 984 * Compute the hash of an extended attribute. 985 */ 986 static inline void ext2_xattr_hash_entry(struct ext2_xattr_header *header, 987 struct ext2_xattr_entry *entry) 988 { 989 __u32 hash = 0; 990 char *name = entry->e_name; 991 int n; 992 993 for (n=0; n < entry->e_name_len; n++) { 994 hash = (hash << NAME_HASH_SHIFT) ^ 995 (hash >> (8*sizeof(hash) - NAME_HASH_SHIFT)) ^ 996 *name++; 997 } 998 999 if (entry->e_value_block == 0 && entry->e_value_size != 0) { 1000 __le32 *value = (__le32 *)((char *)header + 1001 le16_to_cpu(entry->e_value_offs)); 1002 for (n = (le32_to_cpu(entry->e_value_size) + 1003 EXT2_XATTR_ROUND) >> EXT2_XATTR_PAD_BITS; n; n--) { 1004 hash = (hash << VALUE_HASH_SHIFT) ^ 1005 (hash >> (8*sizeof(hash) - VALUE_HASH_SHIFT)) ^ 1006 le32_to_cpu(*value++); 1007 } 1008 } 1009 entry->e_hash = cpu_to_le32(hash); 1010 } 1011 1012 #undef NAME_HASH_SHIFT 1013 #undef VALUE_HASH_SHIFT 1014 1015 #define BLOCK_HASH_SHIFT 16 1016 1017 /* 1018 * ext2_xattr_rehash() 1019 * 1020 * Re-compute the extended attribute hash value after an entry has changed. 1021 */ 1022 static void ext2_xattr_rehash(struct ext2_xattr_header *header, 1023 struct ext2_xattr_entry *entry) 1024 { 1025 struct ext2_xattr_entry *here; 1026 __u32 hash = 0; 1027 1028 ext2_xattr_hash_entry(header, entry); 1029 here = ENTRY(header+1); 1030 while (!IS_LAST_ENTRY(here)) { 1031 if (!here->e_hash) { 1032 /* Block is not shared if an entry's hash value == 0 */ 1033 hash = 0; 1034 break; 1035 } 1036 hash = (hash << BLOCK_HASH_SHIFT) ^ 1037 (hash >> (8*sizeof(hash) - BLOCK_HASH_SHIFT)) ^ 1038 le32_to_cpu(here->e_hash); 1039 here = EXT2_XATTR_NEXT(here); 1040 } 1041 header->h_hash = cpu_to_le32(hash); 1042 } 1043 1044 #undef BLOCK_HASH_SHIFT 1045 1046 #define HASH_BUCKET_BITS 10 1047 1048 struct mb_cache *ext2_xattr_create_cache(void) 1049 { 1050 return mb_cache_create(HASH_BUCKET_BITS); 1051 } 1052 1053 void ext2_xattr_destroy_cache(struct mb_cache *cache) 1054 { 1055 if (cache) 1056 mb_cache_destroy(cache); 1057 } 1058