1 /* 2 * linux/fs/jbd2/recovery.c 3 * 4 * Written by Stephen C. Tweedie <sct@redhat.com>, 1999 5 * 6 * Copyright 1999-2000 Red Hat Software --- 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 recovery routines for the generic filesystem journaling code; 13 * part of the ext2fs journaling system. 14 */ 15 16 #ifndef __KERNEL__ 17 #include "jfs_user.h" 18 #else 19 #include <linux/time.h> 20 #include <linux/fs.h> 21 #include <linux/jbd2.h> 22 #include <linux/errno.h> 23 #include <linux/slab.h> 24 #endif 25 26 /* 27 * Maintain information about the progress of the recovery job, so that 28 * the different passes can carry information between them. 29 */ 30 struct recovery_info 31 { 32 tid_t start_transaction; 33 tid_t end_transaction; 34 35 int nr_replays; 36 int nr_revokes; 37 int nr_revoke_hits; 38 }; 39 40 enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY}; 41 static int do_one_pass(journal_t *journal, 42 struct recovery_info *info, enum passtype pass); 43 static int scan_revoke_records(journal_t *, struct buffer_head *, 44 tid_t, struct recovery_info *); 45 46 #ifdef __KERNEL__ 47 48 /* Release readahead buffers after use */ 49 static void journal_brelse_array(struct buffer_head *b[], int n) 50 { 51 while (--n >= 0) 52 brelse (b[n]); 53 } 54 55 56 /* 57 * When reading from the journal, we are going through the block device 58 * layer directly and so there is no readahead being done for us. We 59 * need to implement any readahead ourselves if we want it to happen at 60 * all. Recovery is basically one long sequential read, so make sure we 61 * do the IO in reasonably large chunks. 62 * 63 * This is not so critical that we need to be enormously clever about 64 * the readahead size, though. 128K is a purely arbitrary, good-enough 65 * fixed value. 66 */ 67 68 #define MAXBUF 8 69 static int do_readahead(journal_t *journal, unsigned int start) 70 { 71 int err; 72 unsigned int max, nbufs, next; 73 unsigned long long blocknr; 74 struct buffer_head *bh; 75 76 struct buffer_head * bufs[MAXBUF]; 77 78 /* Do up to 128K of readahead */ 79 max = start + (128 * 1024 / journal->j_blocksize); 80 if (max > journal->j_maxlen) 81 max = journal->j_maxlen; 82 83 /* Do the readahead itself. We'll submit MAXBUF buffer_heads at 84 * a time to the block device IO layer. */ 85 86 nbufs = 0; 87 88 for (next = start; next < max; next++) { 89 err = jbd2_journal_bmap(journal, next, &blocknr); 90 91 if (err) { 92 printk (KERN_ERR "JBD: bad block at offset %u\n", 93 next); 94 goto failed; 95 } 96 97 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); 98 if (!bh) { 99 err = -ENOMEM; 100 goto failed; 101 } 102 103 if (!buffer_uptodate(bh) && !buffer_locked(bh)) { 104 bufs[nbufs++] = bh; 105 if (nbufs == MAXBUF) { 106 ll_rw_block(READ, nbufs, bufs); 107 journal_brelse_array(bufs, nbufs); 108 nbufs = 0; 109 } 110 } else 111 brelse(bh); 112 } 113 114 if (nbufs) 115 ll_rw_block(READ, nbufs, bufs); 116 err = 0; 117 118 failed: 119 if (nbufs) 120 journal_brelse_array(bufs, nbufs); 121 return err; 122 } 123 124 #endif /* __KERNEL__ */ 125 126 127 /* 128 * Read a block from the journal 129 */ 130 131 static int jread(struct buffer_head **bhp, journal_t *journal, 132 unsigned int offset) 133 { 134 int err; 135 unsigned long long blocknr; 136 struct buffer_head *bh; 137 138 *bhp = NULL; 139 140 if (offset >= journal->j_maxlen) { 141 printk(KERN_ERR "JBD: corrupted journal superblock\n"); 142 return -EIO; 143 } 144 145 err = jbd2_journal_bmap(journal, offset, &blocknr); 146 147 if (err) { 148 printk (KERN_ERR "JBD: bad block at offset %u\n", 149 offset); 150 return err; 151 } 152 153 bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); 154 if (!bh) 155 return -ENOMEM; 156 157 if (!buffer_uptodate(bh)) { 158 /* If this is a brand new buffer, start readahead. 159 Otherwise, we assume we are already reading it. */ 160 if (!buffer_req(bh)) 161 do_readahead(journal, offset); 162 wait_on_buffer(bh); 163 } 164 165 if (!buffer_uptodate(bh)) { 166 printk (KERN_ERR "JBD: Failed to read block at offset %u\n", 167 offset); 168 brelse(bh); 169 return -EIO; 170 } 171 172 *bhp = bh; 173 return 0; 174 } 175 176 177 /* 178 * Count the number of in-use tags in a journal descriptor block. 179 */ 180 181 static int count_tags(journal_t *journal, struct buffer_head *bh) 182 { 183 char * tagp; 184 journal_block_tag_t * tag; 185 int nr = 0, size = journal->j_blocksize; 186 int tag_bytes = journal_tag_bytes(journal); 187 188 tagp = &bh->b_data[sizeof(journal_header_t)]; 189 190 while ((tagp - bh->b_data + tag_bytes) <= size) { 191 tag = (journal_block_tag_t *) tagp; 192 193 nr++; 194 tagp += tag_bytes; 195 if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID))) 196 tagp += 16; 197 198 if (tag->t_flags & cpu_to_be32(JBD2_FLAG_LAST_TAG)) 199 break; 200 } 201 202 return nr; 203 } 204 205 206 /* Make sure we wrap around the log correctly! */ 207 #define wrap(journal, var) \ 208 do { \ 209 if (var >= (journal)->j_last) \ 210 var -= ((journal)->j_last - (journal)->j_first); \ 211 } while (0) 212 213 /** 214 * jbd2_journal_recover - recovers a on-disk journal 215 * @journal: the journal to recover 216 * 217 * The primary function for recovering the log contents when mounting a 218 * journaled device. 219 * 220 * Recovery is done in three passes. In the first pass, we look for the 221 * end of the log. In the second, we assemble the list of revoke 222 * blocks. In the third and final pass, we replay any un-revoked blocks 223 * in the log. 224 */ 225 int jbd2_journal_recover(journal_t *journal) 226 { 227 int err; 228 journal_superblock_t * sb; 229 230 struct recovery_info info; 231 232 memset(&info, 0, sizeof(info)); 233 sb = journal->j_superblock; 234 235 /* 236 * The journal superblock's s_start field (the current log head) 237 * is always zero if, and only if, the journal was cleanly 238 * unmounted. 239 */ 240 241 if (!sb->s_start) { 242 jbd_debug(1, "No recovery required, last transaction %d\n", 243 be32_to_cpu(sb->s_sequence)); 244 journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1; 245 return 0; 246 } 247 248 err = do_one_pass(journal, &info, PASS_SCAN); 249 if (!err) 250 err = do_one_pass(journal, &info, PASS_REVOKE); 251 if (!err) 252 err = do_one_pass(journal, &info, PASS_REPLAY); 253 254 jbd_debug(0, "JBD: recovery, exit status %d, " 255 "recovered transactions %u to %u\n", 256 err, info.start_transaction, info.end_transaction); 257 jbd_debug(0, "JBD: Replayed %d and revoked %d/%d blocks\n", 258 info.nr_replays, info.nr_revoke_hits, info.nr_revokes); 259 260 /* Restart the log at the next transaction ID, thus invalidating 261 * any existing commit records in the log. */ 262 journal->j_transaction_sequence = ++info.end_transaction; 263 264 jbd2_journal_clear_revoke(journal); 265 sync_blockdev(journal->j_fs_dev); 266 return err; 267 } 268 269 /** 270 * jbd2_journal_skip_recovery - Start journal and wipe exiting records 271 * @journal: journal to startup 272 * 273 * Locate any valid recovery information from the journal and set up the 274 * journal structures in memory to ignore it (presumably because the 275 * caller has evidence that it is out of date). 276 * This function does'nt appear to be exorted.. 277 * 278 * We perform one pass over the journal to allow us to tell the user how 279 * much recovery information is being erased, and to let us initialise 280 * the journal transaction sequence numbers to the next unused ID. 281 */ 282 int jbd2_journal_skip_recovery(journal_t *journal) 283 { 284 int err; 285 journal_superblock_t * sb; 286 287 struct recovery_info info; 288 289 memset (&info, 0, sizeof(info)); 290 sb = journal->j_superblock; 291 292 err = do_one_pass(journal, &info, PASS_SCAN); 293 294 if (err) { 295 printk(KERN_ERR "JBD: error %d scanning journal\n", err); 296 ++journal->j_transaction_sequence; 297 } else { 298 #ifdef CONFIG_JBD_DEBUG 299 int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence); 300 #endif 301 jbd_debug(0, 302 "JBD: ignoring %d transaction%s from the journal.\n", 303 dropped, (dropped == 1) ? "" : "s"); 304 journal->j_transaction_sequence = ++info.end_transaction; 305 } 306 307 journal->j_tail = 0; 308 return err; 309 } 310 311 static inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag) 312 { 313 unsigned long long block = be32_to_cpu(tag->t_blocknr); 314 if (tag_bytes > JBD_TAG_SIZE32) 315 block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32; 316 return block; 317 } 318 319 static int do_one_pass(journal_t *journal, 320 struct recovery_info *info, enum passtype pass) 321 { 322 unsigned int first_commit_ID, next_commit_ID; 323 unsigned long next_log_block; 324 int err, success = 0; 325 journal_superblock_t * sb; 326 journal_header_t * tmp; 327 struct buffer_head * bh; 328 unsigned int sequence; 329 int blocktype; 330 int tag_bytes = journal_tag_bytes(journal); 331 332 /* Precompute the maximum metadata descriptors in a descriptor block */ 333 int MAX_BLOCKS_PER_DESC; 334 MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t)) 335 / tag_bytes); 336 337 /* 338 * First thing is to establish what we expect to find in the log 339 * (in terms of transaction IDs), and where (in terms of log 340 * block offsets): query the superblock. 341 */ 342 343 sb = journal->j_superblock; 344 next_commit_ID = be32_to_cpu(sb->s_sequence); 345 next_log_block = be32_to_cpu(sb->s_start); 346 347 first_commit_ID = next_commit_ID; 348 if (pass == PASS_SCAN) 349 info->start_transaction = first_commit_ID; 350 351 jbd_debug(1, "Starting recovery pass %d\n", pass); 352 353 /* 354 * Now we walk through the log, transaction by transaction, 355 * making sure that each transaction has a commit block in the 356 * expected place. Each complete transaction gets replayed back 357 * into the main filesystem. 358 */ 359 360 while (1) { 361 int flags; 362 char * tagp; 363 journal_block_tag_t * tag; 364 struct buffer_head * obh; 365 struct buffer_head * nbh; 366 367 cond_resched(); /* We're under lock_kernel() */ 368 369 /* If we already know where to stop the log traversal, 370 * check right now that we haven't gone past the end of 371 * the log. */ 372 373 if (pass != PASS_SCAN) 374 if (tid_geq(next_commit_ID, info->end_transaction)) 375 break; 376 377 jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n", 378 next_commit_ID, next_log_block, journal->j_last); 379 380 /* Skip over each chunk of the transaction looking 381 * either the next descriptor block or the final commit 382 * record. */ 383 384 jbd_debug(3, "JBD: checking block %ld\n", next_log_block); 385 err = jread(&bh, journal, next_log_block); 386 if (err) 387 goto failed; 388 389 next_log_block++; 390 wrap(journal, next_log_block); 391 392 /* What kind of buffer is it? 393 * 394 * If it is a descriptor block, check that it has the 395 * expected sequence number. Otherwise, we're all done 396 * here. */ 397 398 tmp = (journal_header_t *)bh->b_data; 399 400 if (tmp->h_magic != cpu_to_be32(JBD2_MAGIC_NUMBER)) { 401 brelse(bh); 402 break; 403 } 404 405 blocktype = be32_to_cpu(tmp->h_blocktype); 406 sequence = be32_to_cpu(tmp->h_sequence); 407 jbd_debug(3, "Found magic %d, sequence %d\n", 408 blocktype, sequence); 409 410 if (sequence != next_commit_ID) { 411 brelse(bh); 412 break; 413 } 414 415 /* OK, we have a valid descriptor block which matches 416 * all of the sequence number checks. What are we going 417 * to do with it? That depends on the pass... */ 418 419 switch(blocktype) { 420 case JBD2_DESCRIPTOR_BLOCK: 421 /* If it is a valid descriptor block, replay it 422 * in pass REPLAY; otherwise, just skip over the 423 * blocks it describes. */ 424 if (pass != PASS_REPLAY) { 425 next_log_block += count_tags(journal, bh); 426 wrap(journal, next_log_block); 427 brelse(bh); 428 continue; 429 } 430 431 /* A descriptor block: we can now write all of 432 * the data blocks. Yay, useful work is finally 433 * getting done here! */ 434 435 tagp = &bh->b_data[sizeof(journal_header_t)]; 436 while ((tagp - bh->b_data + tag_bytes) 437 <= journal->j_blocksize) { 438 unsigned long io_block; 439 440 tag = (journal_block_tag_t *) tagp; 441 flags = be32_to_cpu(tag->t_flags); 442 443 io_block = next_log_block++; 444 wrap(journal, next_log_block); 445 err = jread(&obh, journal, io_block); 446 if (err) { 447 /* Recover what we can, but 448 * report failure at the end. */ 449 success = err; 450 printk (KERN_ERR 451 "JBD: IO error %d recovering " 452 "block %ld in log\n", 453 err, io_block); 454 } else { 455 unsigned long long blocknr; 456 457 J_ASSERT(obh != NULL); 458 blocknr = read_tag_block(tag_bytes, 459 tag); 460 461 /* If the block has been 462 * revoked, then we're all done 463 * here. */ 464 if (jbd2_journal_test_revoke 465 (journal, blocknr, 466 next_commit_ID)) { 467 brelse(obh); 468 ++info->nr_revoke_hits; 469 goto skip_write; 470 } 471 472 /* Find a buffer for the new 473 * data being restored */ 474 nbh = __getblk(journal->j_fs_dev, 475 blocknr, 476 journal->j_blocksize); 477 if (nbh == NULL) { 478 printk(KERN_ERR 479 "JBD: Out of memory " 480 "during recovery.\n"); 481 err = -ENOMEM; 482 brelse(bh); 483 brelse(obh); 484 goto failed; 485 } 486 487 lock_buffer(nbh); 488 memcpy(nbh->b_data, obh->b_data, 489 journal->j_blocksize); 490 if (flags & JBD2_FLAG_ESCAPE) { 491 *((__be32 *)bh->b_data) = 492 cpu_to_be32(JBD2_MAGIC_NUMBER); 493 } 494 495 BUFFER_TRACE(nbh, "marking dirty"); 496 set_buffer_uptodate(nbh); 497 mark_buffer_dirty(nbh); 498 BUFFER_TRACE(nbh, "marking uptodate"); 499 ++info->nr_replays; 500 /* ll_rw_block(WRITE, 1, &nbh); */ 501 unlock_buffer(nbh); 502 brelse(obh); 503 brelse(nbh); 504 } 505 506 skip_write: 507 tagp += tag_bytes; 508 if (!(flags & JBD2_FLAG_SAME_UUID)) 509 tagp += 16; 510 511 if (flags & JBD2_FLAG_LAST_TAG) 512 break; 513 } 514 515 brelse(bh); 516 continue; 517 518 case JBD2_COMMIT_BLOCK: 519 /* Found an expected commit block: not much to 520 * do other than move on to the next sequence 521 * number. */ 522 brelse(bh); 523 next_commit_ID++; 524 continue; 525 526 case JBD2_REVOKE_BLOCK: 527 /* If we aren't in the REVOKE pass, then we can 528 * just skip over this block. */ 529 if (pass != PASS_REVOKE) { 530 brelse(bh); 531 continue; 532 } 533 534 err = scan_revoke_records(journal, bh, 535 next_commit_ID, info); 536 brelse(bh); 537 if (err) 538 goto failed; 539 continue; 540 541 default: 542 jbd_debug(3, "Unrecognised magic %d, end of scan.\n", 543 blocktype); 544 brelse(bh); 545 goto done; 546 } 547 } 548 549 done: 550 /* 551 * We broke out of the log scan loop: either we came to the 552 * known end of the log or we found an unexpected block in the 553 * log. If the latter happened, then we know that the "current" 554 * transaction marks the end of the valid log. 555 */ 556 557 if (pass == PASS_SCAN) 558 info->end_transaction = next_commit_ID; 559 else { 560 /* It's really bad news if different passes end up at 561 * different places (but possible due to IO errors). */ 562 if (info->end_transaction != next_commit_ID) { 563 printk (KERN_ERR "JBD: recovery pass %d ended at " 564 "transaction %u, expected %u\n", 565 pass, next_commit_ID, info->end_transaction); 566 if (!success) 567 success = -EIO; 568 } 569 } 570 571 return success; 572 573 failed: 574 return err; 575 } 576 577 578 /* Scan a revoke record, marking all blocks mentioned as revoked. */ 579 580 static int scan_revoke_records(journal_t *journal, struct buffer_head *bh, 581 tid_t sequence, struct recovery_info *info) 582 { 583 jbd2_journal_revoke_header_t *header; 584 int offset, max; 585 int record_len = 4; 586 587 header = (jbd2_journal_revoke_header_t *) bh->b_data; 588 offset = sizeof(jbd2_journal_revoke_header_t); 589 max = be32_to_cpu(header->r_count); 590 591 if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT)) 592 record_len = 8; 593 594 while (offset + record_len <= max) { 595 unsigned long long blocknr; 596 int err; 597 598 if (record_len == 4) 599 blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset))); 600 else 601 blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset))); 602 offset += record_len; 603 err = jbd2_journal_set_revoke(journal, blocknr, sequence); 604 if (err) 605 return err; 606 ++info->nr_revokes; 607 } 608 return 0; 609 } 610