/* * linux/fs/recovery.c * * Written by Stephen C. Tweedie <sct@redhat.com>, 1999 * * Copyright 1999-2000 Red Hat Software --- All Rights Reserved * * This file is part of the Linux kernel and is made available under * the terms of the GNU General Public License, version 2, or at your * option, any later version, incorporated herein by reference. * * Journal recovery routines for the generic filesystem journaling code; * part of the ext2fs journaling system. */ #ifndef __KERNEL__ #include "jfs_user.h" #else #include <linux/time.h> #include <linux/fs.h> #include <linux/jbd.h> #include <linux/errno.h> #include <linux/slab.h> #endif /* * Maintain information about the progress of the recovery job, so that * the different passes can carry information between them. */ struct recovery_info { tid_t start_transaction; tid_t end_transaction; int nr_replays; int nr_revokes; int nr_revoke_hits; }; enum passtype {PASS_SCAN, PASS_REVOKE, PASS_REPLAY}; static int do_one_pass(journal_t *journal, struct recovery_info *info, enum passtype pass); static int scan_revoke_records(journal_t *, struct buffer_head *, tid_t, struct recovery_info *); #ifdef __KERNEL__ /* Release readahead buffers after use */ static void journal_brelse_array(struct buffer_head *b[], int n) { while (--n >= 0) brelse (b[n]); } /* * When reading from the journal, we are going through the block device * layer directly and so there is no readahead being done for us. We * need to implement any readahead ourselves if we want it to happen at * all. Recovery is basically one long sequential read, so make sure we * do the IO in reasonably large chunks. * * This is not so critical that we need to be enormously clever about * the readahead size, though. 128K is a purely arbitrary, good-enough * fixed value. */ #define MAXBUF 8 static int do_readahead(journal_t *journal, unsigned int start) { int err; unsigned int max, nbufs, next; unsigned long blocknr; struct buffer_head *bh; struct buffer_head * bufs[MAXBUF]; /* Do up to 128K of readahead */ max = start + (128 * 1024 / journal->j_blocksize); if (max > journal->j_maxlen) max = journal->j_maxlen; /* Do the readahead itself. We'll submit MAXBUF buffer_heads at * a time to the block device IO layer. */ nbufs = 0; for (next = start; next < max; next++) { err = journal_bmap(journal, next, &blocknr); if (err) { printk (KERN_ERR "JBD: bad block at offset %u\n", next); goto failed; } bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); if (!bh) { err = -ENOMEM; goto failed; } if (!buffer_uptodate(bh) && !buffer_locked(bh)) { bufs[nbufs++] = bh; if (nbufs == MAXBUF) { ll_rw_block(READ, nbufs, bufs); journal_brelse_array(bufs, nbufs); nbufs = 0; } } else brelse(bh); } if (nbufs) ll_rw_block(READ, nbufs, bufs); err = 0; failed: if (nbufs) journal_brelse_array(bufs, nbufs); return err; } #endif /* __KERNEL__ */ /* * Read a block from the journal */ static int jread(struct buffer_head **bhp, journal_t *journal, unsigned int offset) { int err; unsigned long blocknr; struct buffer_head *bh; *bhp = NULL; if (offset >= journal->j_maxlen) { printk(KERN_ERR "JBD: corrupted journal superblock\n"); return -EIO; } err = journal_bmap(journal, offset, &blocknr); if (err) { printk (KERN_ERR "JBD: bad block at offset %u\n", offset); return err; } bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize); if (!bh) return -ENOMEM; if (!buffer_uptodate(bh)) { /* If this is a brand new buffer, start readahead. Otherwise, we assume we are already reading it. */ if (!buffer_req(bh)) do_readahead(journal, offset); wait_on_buffer(bh); } if (!buffer_uptodate(bh)) { printk (KERN_ERR "JBD: Failed to read block at offset %u\n", offset); brelse(bh); return -EIO; } *bhp = bh; return 0; } /* * Count the number of in-use tags in a journal descriptor block. */ static int count_tags(struct buffer_head *bh, int size) { char * tagp; journal_block_tag_t * tag; int nr = 0; tagp = &bh->b_data[sizeof(journal_header_t)]; while ((tagp - bh->b_data + sizeof(journal_block_tag_t)) <= size) { tag = (journal_block_tag_t *) tagp; nr++; tagp += sizeof(journal_block_tag_t); if (!(tag->t_flags & cpu_to_be32(JFS_FLAG_SAME_UUID))) tagp += 16; if (tag->t_flags & cpu_to_be32(JFS_FLAG_LAST_TAG)) break; } return nr; } /* Make sure we wrap around the log correctly! */ #define wrap(journal, var) \ do { \ if (var >= (journal)->j_last) \ var -= ((journal)->j_last - (journal)->j_first); \ } while (0) /** * journal_recover - recovers a on-disk journal * @journal: the journal to recover * * The primary function for recovering the log contents when mounting a * journaled device. * * Recovery is done in three passes. In the first pass, we look for the * end of the log. In the second, we assemble the list of revoke * blocks. In the third and final pass, we replay any un-revoked blocks * in the log. */ int journal_recover(journal_t *journal) { int err; journal_superblock_t * sb; struct recovery_info info; memset(&info, 0, sizeof(info)); sb = journal->j_superblock; /* * The journal superblock's s_start field (the current log head) * is always zero if, and only if, the journal was cleanly * unmounted. */ if (!sb->s_start) { jbd_debug(1, "No recovery required, last transaction %d\n", be32_to_cpu(sb->s_sequence)); journal->j_transaction_sequence = be32_to_cpu(sb->s_sequence) + 1; return 0; } err = do_one_pass(journal, &info, PASS_SCAN); if (!err) err = do_one_pass(journal, &info, PASS_REVOKE); if (!err) err = do_one_pass(journal, &info, PASS_REPLAY); jbd_debug(0, "JBD: recovery, exit status %d, " "recovered transactions %u to %u\n", err, info.start_transaction, info.end_transaction); jbd_debug(0, "JBD: Replayed %d and revoked %d/%d blocks\n", info.nr_replays, info.nr_revoke_hits, info.nr_revokes); /* Restart the log at the next transaction ID, thus invalidating * any existing commit records in the log. */ journal->j_transaction_sequence = ++info.end_transaction; journal_clear_revoke(journal); sync_blockdev(journal->j_fs_dev); return err; } /** * journal_skip_recovery - Start journal and wipe exiting records * @journal: journal to startup * * Locate any valid recovery information from the journal and set up the * journal structures in memory to ignore it (presumably because the * caller has evidence that it is out of date). * This function does'nt appear to be exorted.. * * We perform one pass over the journal to allow us to tell the user how * much recovery information is being erased, and to let us initialise * the journal transaction sequence numbers to the next unused ID. */ int journal_skip_recovery(journal_t *journal) { int err; journal_superblock_t * sb; struct recovery_info info; memset (&info, 0, sizeof(info)); sb = journal->j_superblock; err = do_one_pass(journal, &info, PASS_SCAN); if (err) { printk(KERN_ERR "JBD: error %d scanning journal\n", err); ++journal->j_transaction_sequence; } else { #ifdef CONFIG_JBD_DEBUG int dropped = info.end_transaction - be32_to_cpu(sb->s_sequence); #endif jbd_debug(0, "JBD: ignoring %d transaction%s from the journal.\n", dropped, (dropped == 1) ? "" : "s"); journal->j_transaction_sequence = ++info.end_transaction; } journal->j_tail = 0; return err; } static int do_one_pass(journal_t *journal, struct recovery_info *info, enum passtype pass) { unsigned int first_commit_ID, next_commit_ID; unsigned long next_log_block; int err, success = 0; journal_superblock_t * sb; journal_header_t * tmp; struct buffer_head * bh; unsigned int sequence; int blocktype; /* Precompute the maximum metadata descriptors in a descriptor block */ int MAX_BLOCKS_PER_DESC; MAX_BLOCKS_PER_DESC = ((journal->j_blocksize-sizeof(journal_header_t)) / sizeof(journal_block_tag_t)); /* * First thing is to establish what we expect to find in the log * (in terms of transaction IDs), and where (in terms of log * block offsets): query the superblock. */ sb = journal->j_superblock; next_commit_ID = be32_to_cpu(sb->s_sequence); next_log_block = be32_to_cpu(sb->s_start); first_commit_ID = next_commit_ID; if (pass == PASS_SCAN) info->start_transaction = first_commit_ID; jbd_debug(1, "Starting recovery pass %d\n", pass); /* * Now we walk through the log, transaction by transaction, * making sure that each transaction has a commit block in the * expected place. Each complete transaction gets replayed back * into the main filesystem. */ while (1) { int flags; char * tagp; journal_block_tag_t * tag; struct buffer_head * obh; struct buffer_head * nbh; cond_resched(); /* We're under lock_kernel() */ /* If we already know where to stop the log traversal, * check right now that we haven't gone past the end of * the log. */ if (pass != PASS_SCAN) if (tid_geq(next_commit_ID, info->end_transaction)) break; jbd_debug(2, "Scanning for sequence ID %u at %lu/%lu\n", next_commit_ID, next_log_block, journal->j_last); /* Skip over each chunk of the transaction looking * either the next descriptor block or the final commit * record. */ jbd_debug(3, "JBD: checking block %ld\n", next_log_block); err = jread(&bh, journal, next_log_block); if (err) goto failed; next_log_block++; wrap(journal, next_log_block); /* What kind of buffer is it? * * If it is a descriptor block, check that it has the * expected sequence number. Otherwise, we're all done * here. */ tmp = (journal_header_t *)bh->b_data; if (tmp->h_magic != cpu_to_be32(JFS_MAGIC_NUMBER)) { brelse(bh); break; } blocktype = be32_to_cpu(tmp->h_blocktype); sequence = be32_to_cpu(tmp->h_sequence); jbd_debug(3, "Found magic %d, sequence %d\n", blocktype, sequence); if (sequence != next_commit_ID) { brelse(bh); break; } /* OK, we have a valid descriptor block which matches * all of the sequence number checks. What are we going * to do with it? That depends on the pass... */ switch(blocktype) { case JFS_DESCRIPTOR_BLOCK: /* If it is a valid descriptor block, replay it * in pass REPLAY; otherwise, just skip over the * blocks it describes. */ if (pass != PASS_REPLAY) { next_log_block += count_tags(bh, journal->j_blocksize); wrap(journal, next_log_block); brelse(bh); continue; } /* A descriptor block: we can now write all of * the data blocks. Yay, useful work is finally * getting done here! */ tagp = &bh->b_data[sizeof(journal_header_t)]; while ((tagp - bh->b_data +sizeof(journal_block_tag_t)) <= journal->j_blocksize) { unsigned long io_block; tag = (journal_block_tag_t *) tagp; flags = be32_to_cpu(tag->t_flags); io_block = next_log_block++; wrap(journal, next_log_block); err = jread(&obh, journal, io_block); if (err) { /* Recover what we can, but * report failure at the end. */ success = err; printk (KERN_ERR "JBD: IO error %d recovering " "block %ld in log\n", err, io_block); } else { unsigned long blocknr; J_ASSERT(obh != NULL); blocknr = be32_to_cpu(tag->t_blocknr); /* If the block has been * revoked, then we're all done * here. */ if (journal_test_revoke (journal, blocknr, next_commit_ID)) { brelse(obh); ++info->nr_revoke_hits; goto skip_write; } /* Find a buffer for the new * data being restored */ nbh = __getblk(journal->j_fs_dev, blocknr, journal->j_blocksize); if (nbh == NULL) { printk(KERN_ERR "JBD: Out of memory " "during recovery.\n"); err = -ENOMEM; brelse(bh); brelse(obh); goto failed; } lock_buffer(nbh); memcpy(nbh->b_data, obh->b_data, journal->j_blocksize); if (flags & JFS_FLAG_ESCAPE) { *((__be32 *)bh->b_data) = cpu_to_be32(JFS_MAGIC_NUMBER); } BUFFER_TRACE(nbh, "marking dirty"); set_buffer_uptodate(nbh); mark_buffer_dirty(nbh); BUFFER_TRACE(nbh, "marking uptodate"); ++info->nr_replays; /* ll_rw_block(WRITE, 1, &nbh); */ unlock_buffer(nbh); brelse(obh); brelse(nbh); } skip_write: tagp += sizeof(journal_block_tag_t); if (!(flags & JFS_FLAG_SAME_UUID)) tagp += 16; if (flags & JFS_FLAG_LAST_TAG) break; } brelse(bh); continue; case JFS_COMMIT_BLOCK: /* Found an expected commit block: not much to * do other than move on to the next sequence * number. */ brelse(bh); next_commit_ID++; continue; case JFS_REVOKE_BLOCK: /* If we aren't in the REVOKE pass, then we can * just skip over this block. */ if (pass != PASS_REVOKE) { brelse(bh); continue; } err = scan_revoke_records(journal, bh, next_commit_ID, info); brelse(bh); if (err) goto failed; continue; default: jbd_debug(3, "Unrecognised magic %d, end of scan.\n", blocktype); brelse(bh); goto done; } } done: /* * We broke out of the log scan loop: either we came to the * known end of the log or we found an unexpected block in the * log. If the latter happened, then we know that the "current" * transaction marks the end of the valid log. */ if (pass == PASS_SCAN) info->end_transaction = next_commit_ID; else { /* It's really bad news if different passes end up at * different places (but possible due to IO errors). */ if (info->end_transaction != next_commit_ID) { printk (KERN_ERR "JBD: recovery pass %d ended at " "transaction %u, expected %u\n", pass, next_commit_ID, info->end_transaction); if (!success) success = -EIO; } } return success; failed: return err; } /* Scan a revoke record, marking all blocks mentioned as revoked. */ static int scan_revoke_records(journal_t *journal, struct buffer_head *bh, tid_t sequence, struct recovery_info *info) { journal_revoke_header_t *header; int offset, max; header = (journal_revoke_header_t *) bh->b_data; offset = sizeof(journal_revoke_header_t); max = be32_to_cpu(header->r_count); while (offset < max) { unsigned long blocknr; int err; blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset))); offset += 4; err = journal_set_revoke(journal, blocknr, sequence); if (err) return err; ++info->nr_revokes; } return 0; }