1 /* 2 * linux/fs/jbd2/revoke.c 3 * 4 * Written by Stephen C. Tweedie <sct@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 #endif 95 #include <linux/log2.h> 96 97 static struct kmem_cache *jbd2_revoke_record_cache; 98 static struct kmem_cache *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 journal_head **, int *, 126 struct jbd2_revoke_record_s *, int); 127 static void flush_descriptor(journal_t *, struct journal_head *, int, int); 128 #endif 129 130 /* Utility functions to maintain the revoke table */ 131 132 /* Borrowed from buffer.c: this is a tried and tested block hash function */ 133 static inline int hash(journal_t *journal, unsigned long long block) 134 { 135 struct jbd2_revoke_table_s *table = journal->j_revoke; 136 int hash_shift = table->hash_shift; 137 int hash = (int)block ^ (int)((block >> 31) >> 1); 138 139 return ((hash << (hash_shift - 6)) ^ 140 (hash >> 13) ^ 141 (hash << (hash_shift - 12))) & (table->hash_size - 1); 142 } 143 144 static int insert_revoke_hash(journal_t *journal, unsigned long long blocknr, 145 tid_t seq) 146 { 147 struct list_head *hash_list; 148 struct jbd2_revoke_record_s *record; 149 150 repeat: 151 record = kmem_cache_alloc(jbd2_revoke_record_cache, GFP_NOFS); 152 if (!record) 153 goto oom; 154 155 record->sequence = seq; 156 record->blocknr = blocknr; 157 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; 158 spin_lock(&journal->j_revoke_lock); 159 list_add(&record->hash, hash_list); 160 spin_unlock(&journal->j_revoke_lock); 161 return 0; 162 163 oom: 164 if (!journal_oom_retry) 165 return -ENOMEM; 166 jbd_debug(1, "ENOMEM in %s, retrying\n", __func__); 167 yield(); 168 goto repeat; 169 } 170 171 /* Find a revoke record in the journal's hash table. */ 172 173 static struct jbd2_revoke_record_s *find_revoke_record(journal_t *journal, 174 unsigned long long blocknr) 175 { 176 struct list_head *hash_list; 177 struct jbd2_revoke_record_s *record; 178 179 hash_list = &journal->j_revoke->hash_table[hash(journal, blocknr)]; 180 181 spin_lock(&journal->j_revoke_lock); 182 record = (struct jbd2_revoke_record_s *) hash_list->next; 183 while (&(record->hash) != hash_list) { 184 if (record->blocknr == blocknr) { 185 spin_unlock(&journal->j_revoke_lock); 186 return record; 187 } 188 record = (struct jbd2_revoke_record_s *) record->hash.next; 189 } 190 spin_unlock(&journal->j_revoke_lock); 191 return NULL; 192 } 193 194 void jbd2_journal_destroy_revoke_caches(void) 195 { 196 if (jbd2_revoke_record_cache) { 197 kmem_cache_destroy(jbd2_revoke_record_cache); 198 jbd2_revoke_record_cache = NULL; 199 } 200 if (jbd2_revoke_table_cache) { 201 kmem_cache_destroy(jbd2_revoke_table_cache); 202 jbd2_revoke_table_cache = NULL; 203 } 204 } 205 206 int __init jbd2_journal_init_revoke_caches(void) 207 { 208 J_ASSERT(!jbd2_revoke_record_cache); 209 J_ASSERT(!jbd2_revoke_table_cache); 210 211 jbd2_revoke_record_cache = KMEM_CACHE(jbd2_revoke_record_s, 212 SLAB_HWCACHE_ALIGN|SLAB_TEMPORARY); 213 if (!jbd2_revoke_record_cache) 214 goto record_cache_failure; 215 216 jbd2_revoke_table_cache = KMEM_CACHE(jbd2_revoke_table_s, 217 SLAB_TEMPORARY); 218 if (!jbd2_revoke_table_cache) 219 goto table_cache_failure; 220 return 0; 221 table_cache_failure: 222 jbd2_journal_destroy_revoke_caches(); 223 record_cache_failure: 224 return -ENOMEM; 225 } 226 227 static struct jbd2_revoke_table_s *jbd2_journal_init_revoke_table(int hash_size) 228 { 229 int shift = 0; 230 int tmp = hash_size; 231 struct jbd2_revoke_table_s *table; 232 233 table = kmem_cache_alloc(jbd2_revoke_table_cache, GFP_KERNEL); 234 if (!table) 235 goto out; 236 237 while((tmp >>= 1UL) != 0UL) 238 shift++; 239 240 table->hash_size = hash_size; 241 table->hash_shift = shift; 242 table->hash_table = 243 kmalloc(hash_size * sizeof(struct list_head), GFP_KERNEL); 244 if (!table->hash_table) { 245 kmem_cache_free(jbd2_revoke_table_cache, table); 246 table = NULL; 247 goto out; 248 } 249 250 for (tmp = 0; tmp < hash_size; tmp++) 251 INIT_LIST_HEAD(&table->hash_table[tmp]); 252 253 out: 254 return table; 255 } 256 257 static void jbd2_journal_destroy_revoke_table(struct jbd2_revoke_table_s *table) 258 { 259 int i; 260 struct list_head *hash_list; 261 262 for (i = 0; i < table->hash_size; i++) { 263 hash_list = &table->hash_table[i]; 264 J_ASSERT(list_empty(hash_list)); 265 } 266 267 kfree(table->hash_table); 268 kmem_cache_free(jbd2_revoke_table_cache, table); 269 } 270 271 /* Initialise the revoke table for a given journal to a given size. */ 272 int jbd2_journal_init_revoke(journal_t *journal, int hash_size) 273 { 274 J_ASSERT(journal->j_revoke_table[0] == NULL); 275 J_ASSERT(is_power_of_2(hash_size)); 276 277 journal->j_revoke_table[0] = jbd2_journal_init_revoke_table(hash_size); 278 if (!journal->j_revoke_table[0]) 279 goto fail0; 280 281 journal->j_revoke_table[1] = jbd2_journal_init_revoke_table(hash_size); 282 if (!journal->j_revoke_table[1]) 283 goto fail1; 284 285 journal->j_revoke = journal->j_revoke_table[1]; 286 287 spin_lock_init(&journal->j_revoke_lock); 288 289 return 0; 290 291 fail1: 292 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]); 293 fail0: 294 return -ENOMEM; 295 } 296 297 /* Destroy a journal's revoke table. The table must already be empty! */ 298 void jbd2_journal_destroy_revoke(journal_t *journal) 299 { 300 journal->j_revoke = NULL; 301 if (journal->j_revoke_table[0]) 302 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[0]); 303 if (journal->j_revoke_table[1]) 304 jbd2_journal_destroy_revoke_table(journal->j_revoke_table[1]); 305 } 306 307 308 #ifdef __KERNEL__ 309 310 /* 311 * jbd2_journal_revoke: revoke a given buffer_head from the journal. This 312 * prevents the block from being replayed during recovery if we take a 313 * crash after this current transaction commits. Any subsequent 314 * metadata writes of the buffer in this transaction cancel the 315 * revoke. 316 * 317 * Note that this call may block --- it is up to the caller to make 318 * sure that there are no further calls to journal_write_metadata 319 * before the revoke is complete. In ext3, this implies calling the 320 * revoke before clearing the block bitmap when we are deleting 321 * metadata. 322 * 323 * Revoke performs a jbd2_journal_forget on any buffer_head passed in as a 324 * parameter, but does _not_ forget the buffer_head if the bh was only 325 * found implicitly. 326 * 327 * bh_in may not be a journalled buffer - it may have come off 328 * the hash tables without an attached journal_head. 329 * 330 * If bh_in is non-zero, jbd2_journal_revoke() will decrement its b_count 331 * by one. 332 */ 333 334 int jbd2_journal_revoke(handle_t *handle, unsigned long long blocknr, 335 struct buffer_head *bh_in) 336 { 337 struct buffer_head *bh = NULL; 338 journal_t *journal; 339 struct block_device *bdev; 340 int err; 341 342 might_sleep(); 343 if (bh_in) 344 BUFFER_TRACE(bh_in, "enter"); 345 346 journal = handle->h_transaction->t_journal; 347 if (!jbd2_journal_set_features(journal, 0, 0, JBD2_FEATURE_INCOMPAT_REVOKE)){ 348 J_ASSERT (!"Cannot set revoke feature!"); 349 return -EINVAL; 350 } 351 352 bdev = journal->j_fs_dev; 353 bh = bh_in; 354 355 if (!bh) { 356 bh = __find_get_block(bdev, blocknr, journal->j_blocksize); 357 if (bh) 358 BUFFER_TRACE(bh, "found on hash"); 359 } 360 #ifdef JBD2_EXPENSIVE_CHECKING 361 else { 362 struct buffer_head *bh2; 363 364 /* If there is a different buffer_head lying around in 365 * memory anywhere... */ 366 bh2 = __find_get_block(bdev, blocknr, journal->j_blocksize); 367 if (bh2) { 368 /* ... and it has RevokeValid status... */ 369 if (bh2 != bh && buffer_revokevalid(bh2)) 370 /* ...then it better be revoked too, 371 * since it's illegal to create a revoke 372 * record against a buffer_head which is 373 * not marked revoked --- that would 374 * risk missing a subsequent revoke 375 * cancel. */ 376 J_ASSERT_BH(bh2, buffer_revoked(bh2)); 377 put_bh(bh2); 378 } 379 } 380 #endif 381 382 /* We really ought not ever to revoke twice in a row without 383 first having the revoke cancelled: it's illegal to free a 384 block twice without allocating it in between! */ 385 if (bh) { 386 if (!J_EXPECT_BH(bh, !buffer_revoked(bh), 387 "inconsistent data on disk")) { 388 if (!bh_in) 389 brelse(bh); 390 return -EIO; 391 } 392 set_buffer_revoked(bh); 393 set_buffer_revokevalid(bh); 394 if (bh_in) { 395 BUFFER_TRACE(bh_in, "call jbd2_journal_forget"); 396 jbd2_journal_forget(handle, bh_in); 397 } else { 398 BUFFER_TRACE(bh, "call brelse"); 399 __brelse(bh); 400 } 401 } 402 403 jbd_debug(2, "insert revoke for block %llu, bh_in=%p\n",blocknr, bh_in); 404 err = insert_revoke_hash(journal, blocknr, 405 handle->h_transaction->t_tid); 406 BUFFER_TRACE(bh_in, "exit"); 407 return err; 408 } 409 410 /* 411 * Cancel an outstanding revoke. For use only internally by the 412 * journaling code (called from jbd2_journal_get_write_access). 413 * 414 * We trust buffer_revoked() on the buffer if the buffer is already 415 * being journaled: if there is no revoke pending on the buffer, then we 416 * don't do anything here. 417 * 418 * This would break if it were possible for a buffer to be revoked and 419 * discarded, and then reallocated within the same transaction. In such 420 * a case we would have lost the revoked bit, but when we arrived here 421 * the second time we would still have a pending revoke to cancel. So, 422 * do not trust the Revoked bit on buffers unless RevokeValid is also 423 * set. 424 */ 425 int jbd2_journal_cancel_revoke(handle_t *handle, struct journal_head *jh) 426 { 427 struct jbd2_revoke_record_s *record; 428 journal_t *journal = handle->h_transaction->t_journal; 429 int need_cancel; 430 int did_revoke = 0; /* akpm: debug */ 431 struct buffer_head *bh = jh2bh(jh); 432 433 jbd_debug(4, "journal_head %p, cancelling revoke\n", jh); 434 435 /* Is the existing Revoke bit valid? If so, we trust it, and 436 * only perform the full cancel if the revoke bit is set. If 437 * not, we can't trust the revoke bit, and we need to do the 438 * full search for a revoke record. */ 439 if (test_set_buffer_revokevalid(bh)) { 440 need_cancel = test_clear_buffer_revoked(bh); 441 } else { 442 need_cancel = 1; 443 clear_buffer_revoked(bh); 444 } 445 446 if (need_cancel) { 447 record = find_revoke_record(journal, bh->b_blocknr); 448 if (record) { 449 jbd_debug(4, "cancelled existing revoke on " 450 "blocknr %llu\n", (unsigned long long)bh->b_blocknr); 451 spin_lock(&journal->j_revoke_lock); 452 list_del(&record->hash); 453 spin_unlock(&journal->j_revoke_lock); 454 kmem_cache_free(jbd2_revoke_record_cache, record); 455 did_revoke = 1; 456 } 457 } 458 459 #ifdef JBD2_EXPENSIVE_CHECKING 460 /* There better not be one left behind by now! */ 461 record = find_revoke_record(journal, bh->b_blocknr); 462 J_ASSERT_JH(jh, record == NULL); 463 #endif 464 465 /* Finally, have we just cleared revoke on an unhashed 466 * buffer_head? If so, we'd better make sure we clear the 467 * revoked status on any hashed alias too, otherwise the revoke 468 * state machine will get very upset later on. */ 469 if (need_cancel) { 470 struct buffer_head *bh2; 471 bh2 = __find_get_block(bh->b_bdev, bh->b_blocknr, bh->b_size); 472 if (bh2) { 473 if (bh2 != bh) 474 clear_buffer_revoked(bh2); 475 __brelse(bh2); 476 } 477 } 478 return did_revoke; 479 } 480 481 /* 482 * journal_clear_revoked_flag clears revoked flag of buffers in 483 * revoke table to reflect there is no revoked buffers in the next 484 * transaction which is going to be started. 485 */ 486 void jbd2_clear_buffer_revoked_flags(journal_t *journal) 487 { 488 struct jbd2_revoke_table_s *revoke = journal->j_revoke; 489 int i = 0; 490 491 for (i = 0; i < revoke->hash_size; i++) { 492 struct list_head *hash_list; 493 struct list_head *list_entry; 494 hash_list = &revoke->hash_table[i]; 495 496 list_for_each(list_entry, hash_list) { 497 struct jbd2_revoke_record_s *record; 498 struct buffer_head *bh; 499 record = (struct jbd2_revoke_record_s *)list_entry; 500 bh = __find_get_block(journal->j_fs_dev, 501 record->blocknr, 502 journal->j_blocksize); 503 if (bh) { 504 clear_buffer_revoked(bh); 505 __brelse(bh); 506 } 507 } 508 } 509 } 510 511 /* journal_switch_revoke table select j_revoke for next transaction 512 * we do not want to suspend any processing until all revokes are 513 * written -bzzz 514 */ 515 void jbd2_journal_switch_revoke_table(journal_t *journal) 516 { 517 int i; 518 519 if (journal->j_revoke == journal->j_revoke_table[0]) 520 journal->j_revoke = journal->j_revoke_table[1]; 521 else 522 journal->j_revoke = journal->j_revoke_table[0]; 523 524 for (i = 0; i < journal->j_revoke->hash_size; i++) 525 INIT_LIST_HEAD(&journal->j_revoke->hash_table[i]); 526 } 527 528 /* 529 * Write revoke records to the journal for all entries in the current 530 * revoke hash, deleting the entries as we go. 531 */ 532 void jbd2_journal_write_revoke_records(journal_t *journal, 533 transaction_t *transaction, 534 int write_op) 535 { 536 struct journal_head *descriptor; 537 struct jbd2_revoke_record_s *record; 538 struct jbd2_revoke_table_s *revoke; 539 struct list_head *hash_list; 540 int i, offset, count; 541 542 descriptor = NULL; 543 offset = 0; 544 count = 0; 545 546 /* select revoke table for committing transaction */ 547 revoke = journal->j_revoke == journal->j_revoke_table[0] ? 548 journal->j_revoke_table[1] : journal->j_revoke_table[0]; 549 550 for (i = 0; i < revoke->hash_size; i++) { 551 hash_list = &revoke->hash_table[i]; 552 553 while (!list_empty(hash_list)) { 554 record = (struct jbd2_revoke_record_s *) 555 hash_list->next; 556 write_one_revoke_record(journal, transaction, 557 &descriptor, &offset, 558 record, write_op); 559 count++; 560 list_del(&record->hash); 561 kmem_cache_free(jbd2_revoke_record_cache, record); 562 } 563 } 564 if (descriptor) 565 flush_descriptor(journal, descriptor, offset, write_op); 566 jbd_debug(1, "Wrote %d revoke records\n", count); 567 } 568 569 /* 570 * Write out one revoke record. We need to create a new descriptor 571 * block if the old one is full or if we have not already created one. 572 */ 573 574 static void write_one_revoke_record(journal_t *journal, 575 transaction_t *transaction, 576 struct journal_head **descriptorp, 577 int *offsetp, 578 struct jbd2_revoke_record_s *record, 579 int write_op) 580 { 581 int csum_size = 0; 582 struct journal_head *descriptor; 583 int offset; 584 journal_header_t *header; 585 586 /* If we are already aborting, this all becomes a noop. We 587 still need to go round the loop in 588 jbd2_journal_write_revoke_records in order to free all of the 589 revoke records: only the IO to the journal is omitted. */ 590 if (is_journal_aborted(journal)) 591 return; 592 593 descriptor = *descriptorp; 594 offset = *offsetp; 595 596 /* Do we need to leave space at the end for a checksum? */ 597 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_CSUM_V2)) 598 csum_size = sizeof(struct jbd2_journal_revoke_tail); 599 600 /* Make sure we have a descriptor with space left for the record */ 601 if (descriptor) { 602 if (offset >= journal->j_blocksize - csum_size) { 603 flush_descriptor(journal, descriptor, offset, write_op); 604 descriptor = NULL; 605 } 606 } 607 608 if (!descriptor) { 609 descriptor = jbd2_journal_get_descriptor_buffer(journal); 610 if (!descriptor) 611 return; 612 header = (journal_header_t *) &jh2bh(descriptor)->b_data[0]; 613 header->h_magic = cpu_to_be32(JBD2_MAGIC_NUMBER); 614 header->h_blocktype = cpu_to_be32(JBD2_REVOKE_BLOCK); 615 header->h_sequence = cpu_to_be32(transaction->t_tid); 616 617 /* Record it so that we can wait for IO completion later */ 618 JBUFFER_TRACE(descriptor, "file as BJ_LogCtl"); 619 jbd2_journal_file_buffer(descriptor, transaction, BJ_LogCtl); 620 621 offset = sizeof(jbd2_journal_revoke_header_t); 622 *descriptorp = descriptor; 623 } 624 625 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) { 626 * ((__be64 *)(&jh2bh(descriptor)->b_data[offset])) = 627 cpu_to_be64(record->blocknr); 628 offset += 8; 629 630 } else { 631 * ((__be32 *)(&jh2bh(descriptor)->b_data[offset])) = 632 cpu_to_be32(record->blocknr); 633 offset += 4; 634 } 635 636 *offsetp = offset; 637 } 638 639 static void jbd2_revoke_csum_set(journal_t *j, 640 struct journal_head *descriptor) 641 { 642 struct jbd2_journal_revoke_tail *tail; 643 __u32 csum; 644 645 if (!JBD2_HAS_INCOMPAT_FEATURE(j, JBD2_FEATURE_INCOMPAT_CSUM_V2)) 646 return; 647 648 tail = (struct jbd2_journal_revoke_tail *) 649 (jh2bh(descriptor)->b_data + j->j_blocksize - 650 sizeof(struct jbd2_journal_revoke_tail)); 651 tail->r_checksum = 0; 652 csum = jbd2_chksum(j, j->j_csum_seed, jh2bh(descriptor)->b_data, 653 j->j_blocksize); 654 tail->r_checksum = cpu_to_be32(csum); 655 } 656 657 /* 658 * Flush a revoke descriptor out to the journal. If we are aborting, 659 * this is a noop; otherwise we are generating a buffer which needs to 660 * be waited for during commit, so it has to go onto the appropriate 661 * journal buffer list. 662 */ 663 664 static void flush_descriptor(journal_t *journal, 665 struct journal_head *descriptor, 666 int offset, int write_op) 667 { 668 jbd2_journal_revoke_header_t *header; 669 struct buffer_head *bh = jh2bh(descriptor); 670 671 if (is_journal_aborted(journal)) { 672 put_bh(bh); 673 return; 674 } 675 676 header = (jbd2_journal_revoke_header_t *) jh2bh(descriptor)->b_data; 677 header->r_count = cpu_to_be32(offset); 678 jbd2_revoke_csum_set(journal, descriptor); 679 680 set_buffer_jwrite(bh); 681 BUFFER_TRACE(bh, "write"); 682 set_buffer_dirty(bh); 683 write_dirty_buffer(bh, write_op); 684 } 685 #endif 686 687 /* 688 * Revoke support for recovery. 689 * 690 * Recovery needs to be able to: 691 * 692 * record all revoke records, including the tid of the latest instance 693 * of each revoke in the journal 694 * 695 * check whether a given block in a given transaction should be replayed 696 * (ie. has not been revoked by a revoke record in that or a subsequent 697 * transaction) 698 * 699 * empty the revoke table after recovery. 700 */ 701 702 /* 703 * First, setting revoke records. We create a new revoke record for 704 * every block ever revoked in the log as we scan it for recovery, and 705 * we update the existing records if we find multiple revokes for a 706 * single block. 707 */ 708 709 int jbd2_journal_set_revoke(journal_t *journal, 710 unsigned long long blocknr, 711 tid_t sequence) 712 { 713 struct jbd2_revoke_record_s *record; 714 715 record = find_revoke_record(journal, blocknr); 716 if (record) { 717 /* If we have multiple occurrences, only record the 718 * latest sequence number in the hashed record */ 719 if (tid_gt(sequence, record->sequence)) 720 record->sequence = sequence; 721 return 0; 722 } 723 return insert_revoke_hash(journal, blocknr, sequence); 724 } 725 726 /* 727 * Test revoke records. For a given block referenced in the log, has 728 * that block been revoked? A revoke record with a given transaction 729 * sequence number revokes all blocks in that transaction and earlier 730 * ones, but later transactions still need replayed. 731 */ 732 733 int jbd2_journal_test_revoke(journal_t *journal, 734 unsigned long long blocknr, 735 tid_t sequence) 736 { 737 struct jbd2_revoke_record_s *record; 738 739 record = find_revoke_record(journal, blocknr); 740 if (!record) 741 return 0; 742 if (tid_gt(sequence, record->sequence)) 743 return 0; 744 return 1; 745 } 746 747 /* 748 * Finally, once recovery is over, we need to clear the revoke table so 749 * that it can be reused by the running filesystem. 750 */ 751 752 void jbd2_journal_clear_revoke(journal_t *journal) 753 { 754 int i; 755 struct list_head *hash_list; 756 struct jbd2_revoke_record_s *record; 757 struct jbd2_revoke_table_s *revoke; 758 759 revoke = journal->j_revoke; 760 761 for (i = 0; i < revoke->hash_size; i++) { 762 hash_list = &revoke->hash_table[i]; 763 while (!list_empty(hash_list)) { 764 record = (struct jbd2_revoke_record_s*) hash_list->next; 765 list_del(&record->hash); 766 kmem_cache_free(jbd2_revoke_record_cache, record); 767 } 768 } 769 } 770