1 /* 2 * linux/fs/jbd2/revoke.c 3 * 4 * Written by Stephen C. Tweedie <sct (at) redhat.com>, 2000 5 * 6 * Copyright 2000 Red Hat corp --- All Rights Reserved 7 * 8 * This file is part of the Linux kernel and is made available under 9 * the terms of the GNU General Public License, version 2, or at your 10 * option, any later version, incorporated herein by reference. 11 * 12 * Journal revoke routines for the generic filesystem journaling code; 13 * part of the ext2fs journaling system. 14 * 15 * Revoke is the mechanism used to prevent old log records for deleted 16 * metadata from being replayed on top of newer data using the same 17 * blocks. The revoke mechanism is used in two separate places: 18 * 19 * + Commit: during commit we write the entire list of the current 20 * transaction's revoked blocks to the journal 21 * 22 * + Recovery: during recovery we record the transaction ID of all 23 * revoked blocks. If there are multiple revoke records in the log 24 * for a single block, only the last one counts, and if there is a log 25 * entry for a block beyond the last revoke, then that log entry still 26 * gets replayed. 27 * 28 * We can get interactions between revokes and new log data within a 29 * single transaction: 30 * 31 * Block is revoked and then journaled: 32 * The desired end result is the journaling of the new block, so we 33 * cancel the revoke before the transaction commits. 34 * 35 * Block is journaled and then revoked: 36 * The revoke must take precedence over the write of the block, so we 37 * need either to cancel the journal entry or to write the revoke 38 * later in the log than the log block. In this case, we choose the 39 * latter: journaling a block cancels any revoke record for that block 40 * in the current transaction, so any revoke for that block in the 41 * transaction must have happened after the block was journaled and so 42 * the revoke must take precedence. 43 * 44 * Block is revoked and then written as data: 45 * The data write is allowed to succeed, but the revoke is _not_ 46 * cancelled. We still need to prevent old log records from 47 * overwriting the new data. We don't even need to clear the revoke 48 * bit here. 49 * 50 * We cache revoke status of a buffer in the current transaction in b_states 51 * bits. As the name says, revokevalid flag indicates that the cached revoke 52 * status of a buffer is valid and we can rely on the cached status. 53 * 54 * Revoke information on buffers is a tri-state value: 55 * 56 * RevokeValid clear: no cached revoke status, need to look it up 57 * RevokeValid set, Revoked clear: 58 * buffer has not been revoked, and cancel_revoke 59 * need do nothing. 60 * RevokeValid set, Revoked set: 61 * buffer has been revoked. 62 * 63 * Locking rules: 64 * We keep two hash tables of revoke records. One hashtable belongs to the 65 * running transaction (is pointed to by journal->j_revoke), the other one 66 * belongs to the committing transaction. Accesses to the second hash table 67 * happen only from the kjournald and no other thread touches this table. Also 68 * journal_switch_revoke_table() which switches which hashtable belongs to the 69 * running and which to the committing transaction is called only from 70 * kjournald. Therefore we need no locks when accessing the hashtable belonging 71 * to the committing transaction. 72 * 73 * All users operating on the hash table belonging to the running transaction 74 * have a handle to the transaction. Therefore they are safe from kjournald 75 * switching hash tables under them. For operations on the lists of entries in 76 * the hash table j_revoke_lock is used. 77 * 78 * Finally, also replay code uses the hash tables but at this moment no one else 79 * can touch them (filesystem isn't mounted yet) and hence no locking is 80 * needed. 81 */ 82 83 #ifndef __KERNEL__ 84 #include "jfs_user.h" 85 #else 86 #include <linux/time.h> 87 #include <linux/fs.h> 88 #include <linux/jbd2.h> 89 #include <linux/errno.h> 90 #include <linux/slab.h> 91 #include <linux/list.h> 92 #include <linux/init.h> 93 #include <linux/bio.h> 94 #include <linux/log2.h> 95 #endif 96 97 static lkmem_cache_t *jbd2_revoke_record_cache; 98 static lkmem_cache_t *jbd2_revoke_table_cache; 99 100 /* Each revoke record represents one single revoked block. During 101 journal replay, this involves recording the transaction ID of the 102 last transaction to revoke this block. */ 103 104 struct jbd2_revoke_record_s 105 { 106 struct list_head hash; 107 tid_t sequence; /* Used for recovery only */ 108 unsigned long long blocknr; 109 }; 110 111 112 /* The revoke table is just a simple hash table of revoke records. */ 113 struct jbd2_revoke_table_s 114 { 115 /* It is conceivable that we might want a larger hash table 116 * for recovery. Must be a power of two. */ 117 int hash_size; 118 int hash_shift; 119 struct list_head *hash_table; 120 }; 121 122 123 #ifdef __KERNEL__ 124 static void write_one_revoke_record(journal_t *, transaction_t *, 125 struct list_head *, 126 struct buffer_head **, int *, 127 struct jbd2_revoke_record_s *, int); 128 static void flush_descriptor(journal_t *, struct buffer_head *, int, int); 129 #endif 130 131 /* Utility functions to maintain the revoke table */ 132 133 /* Borrowed from buffer.c: this is a tried and tested block hash function */ 134 static inline int hash(journal_t *journal, unsigned long long block) 135 { 136 struct jbd2_revoke_table_s *table = journal->j_revoke; 137 138 return (hash_64(block, table->hash_shift)); 139 } 140 141 static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr, 142 tid_t seq) 143 { 144 struct list_head *hash_list; 145 struct jbd2_revoke_record_s *record; 146 147 repeat: 148 record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS); 149 if (!record) 150 goto oom; 151 152 record->sequence = seq; 153 record->blocknr = blocknr; 154 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; 155 spin_lock(&journal->j_revoke_lock); 156 list_add(&record->hash, hash_list); 157 spin_unlock(&journal->j_revoke_lock); 158 return 0; 159 160 oom: 161 if (!journal_oom_retry) 162 return -ENOMEM; 163 jbd_debug(1, "ENOMEM in %s, retrying\n", __func__); 164 yield(); 165 goto repeat; 166 } 167 168 /* Find a revoke record in the journal's hash table. */ 169 170 static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal, 171 unsigned long long blocknr) 172 { 173 struct list_head *hash_list; 174 struct jbd2_revoke_record_s *record; 175 176 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; 177 178 spin_lock(&journal->j_revoke_lock); 179 record = (struct jbd2_revoke_record_s *) hash_list->next; 180 while (&(record->hash) != hash_list) { 181 if (record->blocknr == blocknr) { 182 spin_unlock(&journal->j_revoke_lock); 183 return record; 184 } 185 record = (struct jbd2_revoke_record_s *) record->hash.next; 186 } 187 spin_unlock(&journal->j_revoke_lock); 188 return NULL; 189 } 190 191 void journal_destroy_revoke_caches(void) 192 { 193 if (jbd2_revoke_record_cache) { 194 kmem_cache_destroy(jbd2_revoke_record_cache); 195 jbd2_revoke_record_cache = NULL; 196 } 197 if (jbd2_revoke_table_cache) { 198 kmem_cache_destroy(jbd2_revoke_table_cache); 199 jbd2_revoke_table_cache = NULL; 200 } 201 } 202 203 int __init journal_init_revoke_caches(void) 204 { 205 J_ASSERT(!jbd2_revoke_record_cache); 206 J_ASSERT(!jbd2_revoke_table_cache); 207 208 jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s, 209 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY); 210 if (!jbd2_revoke_record_cache) 211 goto record_cache_failure; 212 213 jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s, 214 SLAB_TEMPORARY); 215 if (!jbd2_revoke_table_cache) 216 goto table_cache_failure; 217 return 0; 218 table_cache_failure: 219 journal_destroy_revoke_caches(); 220 record_cache_failure: 221 return -ENOMEM; 222 } 223 224 static struct jbd2_revoke_table_s *journal_init_revoke_table(int hash_size) 225 { 226 int shift = 0; 227 int tmp = hash_size; 228 struct jbd2_revoke_table_s *table; 229 230 table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL); 231 if (!table) 232 goto out; 233 234 while((tmp >>= 1UL) != 0UL) 235 shift++; 236 237 table->hash_size = hash_size; 238 table->hash_shift = shift; 239 table->hash_table = 240 kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL); 241 if (!table->hash_table) { 242 kmem_cache_free(jbd2_revoke_table_cache, table); 243 table = NULL; 244 goto out; 245 } 246 247 for (tmp = 0; tmp < hash_size; tmp++) 248 INIT_LIST_HEAD(&table->hash_table[tmp]); 249 250 out: 251 return table; 252 } 253 254 static void journal_destroy_revoke_table(struct jbd2_revoke_table_s *table) 255 { 256 int i; 257 struct list_head *hash_list; 258 259 for (i = 0; i < table->hash_size; i++) { 260 hash_list = &table->hash_table[i]; 261 J_ASSERT(list_empty(hash_list)); 262 } 263 264 kfree(table->hash_table); 265 kmem_cache_free(jbd2_revoke_table_cache, table); 266 } 267 268 /* Initialise the revoke table for a given journal to a given size. */ 269 int journal_init_revoke(journal_t *journal, int hash_size) 270 { 271 J_ASSERT(journal->j_revoke_table[0] == NULL); 272 J_ASSERT(is_power_of_2(hash_size)); 273 274 journal->j_revoke_table[0] = journal_init_revoke_table(hash_size); 275 if (!journal->j_revoke_table[0]) 276 goto fail0; 277 278 journal->j_revoke_table[1] = journal_init_revoke_table(hash_size); 279 if (!journal->j_revoke_table[1]) 280 goto fail1; 281 282 journal->j_revoke = journal->j_revoke_table[1]; 283 284 spin_lock_init(&journal->j_revoke_lock); 285 286 return 0; 287 288 fail1: 289 journal_destroy_revoke_table(journal->j_revoke_table[0]); 290 fail0: 291 return -ENOMEM; 292 } 293 294 /* Destroy a journal's revoke table. The table must already be empty! */ 295 void journal_destroy_revoke(journal_t *journal) 296 { 297 journal->j_revoke = NULL; 298 if (journal->j_revoke_table[0]) 299 journal_destroy_revoke_table(journal->j_revoke_table[0]); 300 if (journal->j_revoke_table[1]) 301 journal_destroy_revoke_table(journal->j_revoke_table[1]); 302 } 303 304 305 #ifdef __KERNEL__ 306 307 /* 308 * journal_revoke: revoke a given buffer_head from the journal. This 309 * prevents the block from being replayed during recovery if we take a 310 * crash after this current transaction commits. Any subsequent 311 * metadata writes of the buffer in this transaction cancel the 312 * revoke. 313 * 314 * Note that this call may block --- it is up to the caller to make 315 * sure that there are no further calls to journal_write_metadata 316 * before the revoke is complete. In ext3, this implies calling the 317 * revoke before clearing the block bitmap when we are deleting 318 * metadata. 319 * 320 * Revoke performs a journal_forget on any buffer_head passed in as a 321 * parameter, but does _not_ forget the buffer_head if the bh was only 322 * found implicitly. 323 * 324 * bh_in may not be a journalled buffer - it may have come off 325 * the hash tables without an attached journal_head. 326 * 327 * If bh_in is non-zero, journal_revoke() will decrement its b_count 328 * by one. 329 */ 330 331 int journal_revoke(handle_t *handle, unsigned long long blocknr, 332 struct buffer_head *bh_in) 333 { 334 struct buffer_head *bh = NULL; 335 journal_t *journal; 336 struct block_device *bdev; 337 int err; 338 339 might_sleep(); 340 if (bh_in) 341 BUFFER_TRACE(bh_in, "enter"); 342 343 journal = handle->h_transaction->t_journal; 344 if (!journal_set_features(journal, 0, 0, JFS_FEATURE_INCOMPAT_REVOKE)){ 345 J_ASSERT (!"Cannot set revoke feature!"); 346 return -EINVAL; 347 } 348 349 bdev = journal->j_fs_dev; 350 bh = bh_in; 351 352 if (!bh) { 353 bh = __find_get_block(bdev, blocknr, journal->j_blocksize); 354 if (bh) 355 BUFFER_TRACE(bh, "found on hash"); 356 } 357 #ifdef JFS_EXPENSIVE_CHECKING 358 else { 359 struct buffer_head *bh2; 360 361 /* If there is a different buffer_head lying around in 362 * memory anywhere... */ 363 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize); 364 if (bh2) { 365 /* ... and it has RevokeValid status... */ 366 if (bh2 != bh && buffer_revokevalid(bh2)) 367 /* ...then it better be revoked too, 368 * since it's illegal to create a revoke 369 * record against a buffer_head which is 370 * not marked revoked --- that would 371 * risk missing a subsequent revoke 372 * cancel. */ 373 J_ASSERT_BH(bh2, buffer_revoked(bh2)); 374 put_bh(bh2); 375 } 376 } 377 #endif 378 379 /* We really ought not ever to revoke twice in a row without 380 first having the revoke cancelled: it's illegal to free a 381 block twice without allocating it in between! */ 382 if (bh) { 383 if (!J_EXPECT_BH(bh, !buffer_revoked(bh), 384 "inconsistent data on disk")) { 385 if (!bh_in) 386 brelse(bh); 387 return -EIO; 388 } 389 set_buffer_revoked(bh); 390 set_buffer_revokevalid(bh); 391 if (bh_in) { 392 BUFFER_TRACE(bh_in, "call journal_forget"); 393 journal_forget(handle, bh_in); 394 } else { 395 BUFFER_TRACE(bh, "call brelse"); 396 __brelse(bh); 397 } 398 } 399 400 jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in); 401 err = insert_revoke_hash(journal, blocknr, 402 handle->h_transaction->t_tid); 403 BUFFER_TRACE(bh_in, "exit"); 404 return err; 405 } 406 407 /* 408 * Cancel an outstanding revoke. For use only internally by the 409 * journaling code (called from journal_get_write_access). 410 * 411 * We trust buffer_revoked() on the buffer if the buffer is already 412 * being journaled: if there is no revoke pending on the buffer, then we 413 * don't do anything here. 414 * 415 * This would break if it were possible for a buffer to be revoked and 416 * discarded, and then reallocated within the same transaction. In such 417 * a case we would have lost the revoked bit, but when we arrived here 418 * the second time we would still have a pending revoke to cancel. So, 419 * do not trust the Revoked bit on buffers unless RevokeValid is also 420 * set. 421 */ 422 int journal_cancel_revoke(handle_t *handle, struct journal_head *jh) 423 { 424 struct jbd2_revoke_record_s *record; 425 journal_t *journal = handle->h_transaction->t_journal; 426 int need_cancel; 427 int did_revoke = 0; /* akpm: debug */ 428 struct buffer_head *bh = jh2bh(jh); 429 430 jbd_debug(4, "journal_head %p, canceling revoke\n", jh); 431 432 /* Is the existing Revoke bit valid? If so, we trust it, and 433 * only perform the full cancel if the revoke bit is set. If 434 * not, we can't trust the revoke bit, and we need to do the 435 * full search for a revoke record. */ 436 if (test_set_buffer_revokevalid(bh)) { 437 need_cancel = test_clear_buffer_revoked(bh); 438 } else { 439 need_cancel = 1; 440 clear_buffer_revoked(bh); 441 } 442 443 if (need_cancel) { 444 record = find_revoke_record(journal, bh->b_blocknr); 445 if (record) { 446 jbd_debug(4, "cancelled existing revoke on " 447 "blocknr %llu\n", (unsigned long long)bh->b_blocknr); 448 spin_lock(&journal->j_revoke_lock); 449 list_del(&record->hash); 450 spin_unlock(&journal->j_revoke_lock); 451 kmem_cache_free(jbd2_revoke_record_cache, record); 452 did_revoke = 1; 453 } 454 } 455 456 #ifdef JFS_EXPENSIVE_CHECKING 457 /* There better not be one left behind by now! */ 458 record = find_revoke_record(journal, bh->b_blocknr); 459 J_ASSERT_JH(jh, record == NULL); 460 #endif 461 462 /* Finally, have we just cleared revoke on an unhashed 463 * buffer_head? If so, we'd better make sure we clear the 464 * revoked status on any hashed alias too, otherwise the revoke 465 * state machine will get very upset later on. */ 466 if (need_cancel) { 467 struct buffer_head *bh2; 468 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size); 469 if (bh2) { 470 if (bh2 != bh) 471 clear_buffer_revoked(bh2); 472 __brelse(bh2); 473 } 474 } 475 return did_revoke; 476 } 477 478 /* 479 * journal_clear_revoked_flag clears revoked flag of buffers in 480 * revoke table to reflect there is no revoked buffers in the next 481 * transaction which is going to be started. 482 */ 483 void jbd2_clear_buffer_revoked_flags(journal_t *journal) 484 { 485 struct jbd2_revoke_table_s *revoke = journal->j_revoke; 486 int i = 0; 487 488 for (i = 0; i < revoke->hash_size; i++) { 489 struct list_head *hash_list; 490 struct list_head *list_entry; 491 hash_list = &revoke->hash_table[i]; 492 493 list_for_each(list_entry, hash_list) { 494 struct jbd2_revoke_record_s *record; 495 struct buffer_head *bh; 496 record = (struct jbd2_revoke_record_s *)list_entry; 497 bh = __find_get_block(journal->j_fs_dev, 498 record->blocknr, 499 journal->j_blocksize); 500 if (bh) { 501 clear_buffer_revoked(bh); 502 __brelse(bh); 503 } 504 } 505 } 506 } 507 508 /* journal_switch_revoke table select j_revoke for next transaction 509 * we do not want to suspend any processing until all revokes are 510 * written -bzzz 511 */ 512 void journal_switch_revoke_table(journal_t *journal) 513 { 514 int i; 515 516 if (journal->j_revoke == journal->j_revoke_table[0]) 517 journal->j_revoke = journal->j_revoke_table[1]; 518 else 519 journal->j_revoke = journal->j_revoke_table[0]; 520 521 for (i = 0; i < journal->j_revoke->hash_size; i++) 522 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]); 523 } 524 525 /* 526 * Write revoke records to the journal for all entries in the current 527 * revoke hash, deleting the entries as we go. 528 */ 529 void journal_write_revoke_records(journal_t *journal, 530 transaction_t *transaction, 531 struct list_head *log_bufs, 532 int write_op) 533 { 534 struct buffer_head *descriptor; 535 struct jbd2_revoke_record_s *record; 536 struct jbd2_revoke_table_s *revoke; 537 struct list_head *hash_list; 538 int i, offset, count; 539 540 descriptor = NULL; 541 offset = 0; 542 count = 0; 543 544 /* select revoke table for committing transaction */ 545 revoke = journal->j_revoke == journal->j_revoke_table[0] ? 546 journal->j_revoke_table[1] : journal->j_revoke_table[0]; 547 548 for (i = 0; i < revoke->hash_size; i++) { 549 hash_list = &revoke->hash_table[i]; 550 551 while (!list_empty(hash_list)) { 552 record = (struct jbd2_revoke_record_s *) 553 hash_list->next; 554 write_one_revoke_record(journal, transaction, log_bufs, 555 &descriptor, &offset, 556 record, write_op); 557 count++; 558 list_del(&record->hash); 559 kmem_cache_free(jbd2_revoke_record_cache, record); 560 } 561 } 562 if (descriptor) 563 flush_descriptor(journal, descriptor, offset, write_op); 564 jbd_debug(1, "Wrote %d revoke records\n", count); 565 } 566 567 /* 568 * Write out one revoke record. We need to create a new descriptor 569 * block if the old one is full or if we have not already created one. 570 */ 571 572 static void write_one_revoke_record(journal_t *journal, 573 transaction_t *transaction, 574 struct list_head *log_bufs, 575 struct buffer_head **descriptorp, 576 int *offsetp, 577 struct jbd2_revoke_record_s *record, 578 int write_op) 579 { 580 int csum_size = 0; 581 struct buffer_head *descriptor; 582 int sz, offset; 583 journal_header_t *header; 584 585 /* If we are already aborting, this all becomes a noop. We 586 still need to go round the loop in 587 journal_write_revoke_records in order to free all of the 588 revoke records: only the IO to the journal is omitted. */ 589 if (is_journal_aborted(journal)) 590 return; 591 592 descriptor = *descriptorp; 593 offset = *offsetp; 594 595 /* Do we need to leave space at the end for a checksum? */ 596 if (journal_has_csum_v2or3(journal)) 597 csum_size = sizeof(struct journal_revoke_tail); 598 599 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) 600 sz = 8; 601 else 602 sz = 4; 603 604 /* Make sure we have a descriptor with space left for the record */ 605 if (descriptor) { 606 if (offset + sz > journal->j_blocksize - csum_size) { 607 flush_descriptor(journal, descriptor, offset, write_op); 608 descriptor = NULL; 609 } 610 } 611 612 if (!descriptor) { 613 descriptor = journal_get_descriptor_buffer(journal); 614 if (!descriptor) 615 return; 616 header = (journal_header_t *)descriptor->b_data; 617 header->h_magic = ext2fs_cpu_to_be32(JFS_MAGIC_NUMBER); 618 header->h_blocktype = ext2fs_cpu_to_be32(JFS_REVOKE_BLOCK); 619 header->h_sequence = ext2fs_cpu_to_be32(transaction->t_tid); 620 621 /* Record it so that we can wait for IO completion later */ 622 BUFFER_TRACE(descriptor, "file in log_bufs"); 623 jbd2_file_log_bh(log_bufs, descriptor); 624 625 offset = sizeof(journal_revoke_header_t); 626 *descriptorp = descriptor; 627 } 628 629 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) { 630 * ((__be64 *)(&descriptor->b_data[offset])) = 631 cpu_to_be64(record->blocknr); 632 else 633 * ((__be32 *)(&descriptor->b_data[offset])) = 634 cpu_to_be32(record->blocknr); 635 offset += sz; 636 637 *offsetp = offset; 638 } 639 640 static void jbd2_revoke_csum_set(journal_t *j, struct buffer_head *bh) 641 { 642 struct journal_revoke_tail *tail; 643 __u32 csum; 644 645 if (!journal_has_csum_v2or3(j)) 646 return; 647 648 tail = (struct journal_revoke_tail *)(bh->b_data + j->j_blocksize - 649 sizeof(struct journal_revoke_tail)); 650 tail->r_checksum = 0; 651 csum = jbd2_chksum(j, j->j_csum_seed, bh->b_data, j->j_blocksize); 652 tail->r_checksum = ext2fs_cpu_to_be32(csum); 653 } 654 655 /* 656 * Flush a revoke descriptor out to the journal. If we are aborting, 657 * this is a noop; otherwise we are generating a buffer which needs to 658 * be waited for during commit, so it has to go onto the appropriate 659 * journal buffer list. 660 */ 661 662 static void flush_descriptor(journal_t *journal, 663 struct buffer_head *descriptor, 664 int offset, int write_op) 665 { 666 journal_revoke_header_t *header; 667 668 if (is_journal_aborted(journal)) { 669 put_bh(descriptor); 670 return; 671 } 672 673 header = (journal_revoke_header_t *)descriptor->b_data; 674 header->r_count = ext2fs_cpu_to_be32(offset); 675 jbd2_revoke_csum_set(journal, descriptor); 676 677 set_buffer_jwrite(descriptor); 678 BUFFER_TRACE(descriptor, "write"); 679 set_buffer_dirty(descriptor); 680 write_dirty_buffer(descriptor, write_op); 681 } 682 #endif 683 684 /* 685 * Revoke support for recovery. 686 * 687 * Recovery needs to be able to: 688 * 689 * record all revoke records, including the tid of the latest instance 690 * of each revoke in the journal 691 * 692 * check whether a given block in a given transaction should be replayed 693 * (ie. has not been revoked by a revoke record in that or a subsequent 694 * transaction) 695 * 696 * empty the revoke table after recovery. 697 */ 698 699 /* 700 * First, setting revoke records. We create a new revoke record for 701 * every block ever revoked in the log as we scan it for recovery, and 702 * we update the existing records if we find multiple revokes for a 703 * single block. 704 */ 705 706 int journal_set_revoke(journal_t *journal, 707 unsigned long long blocknr, 708 tid_t sequence) 709 { 710 struct jbd2_revoke_record_s *record; 711 712 record = find_revoke_record(journal, blocknr); 713 if (record) { 714 /* If we have multiple occurrences, only record the 715 * latest sequence number in the hashed record */ 716 if (tid_gt(sequence, record->sequence)) 717 record->sequence = sequence; 718 return 0; 719 } 720 return insert_revoke_hash(journal, blocknr, sequence); 721 } 722 723 /* 724 * Test revoke records. For a given block referenced in the log, has 725 * that block been revoked? A revoke record with a given transaction 726 * sequence number revokes all blocks in that transaction and earlier 727 * ones, but later transactions still need replayed. 728 */ 729 730 int journal_test_revoke(journal_t *journal, 731 unsigned long long blocknr, 732 tid_t sequence) 733 { 734 struct jbd2_revoke_record_s *record; 735 736 record = find_revoke_record(journal, blocknr); 737 if (!record) 738 return 0; 739 if (tid_gt(sequence, record->sequence)) 740 return 0; 741 return 1; 742 } 743 744 /* 745 * Finally, once recovery is over, we need to clear the revoke table so 746 * that it can be reused by the running filesystem. 747 */ 748 749 void journal_clear_revoke(journal_t *journal) 750 { 751 int i; 752 struct list_head *hash_list; 753 struct jbd2_revoke_record_s *record; 754 struct jbd2_revoke_table_s *revoke; 755 756 revoke = journal->j_revoke; 757 758 for (i = 0; i < revoke->hash_size; i++) { 759 hash_list = &revoke->hash_table[i]; 760 while (!list_empty(hash_list)) { 761 record = (struct jbd2_revoke_record_s*) hash_list->next; 762 list_del(&record->hash); 763 kmem_cache_free(jbd2_revoke_record_cache, record); 764 } 765 } 766 } 767
