+++ /dev/null
-/*
- * linux/fs/jbd/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/blkdev.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 int 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 int 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, err2;
- 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(1, "JBD: recovery, exit status %d, "
- "recovered transactions %u to %u\n",
- err, info.start_transaction, info.end_transaction);
- jbd_debug(1, "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);
- err2 = sync_blockdev(journal->j_fs_dev);
- if (!err)
- err = err2;
- /* Flush disk caches to get replayed data on the permanent storage */
- if (journal->j_flags & JFS_BARRIER) {
- err2 = blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);
- if (!err)
- err = err2;
- }
-
- 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;
- struct recovery_info info;
-
- memset (&info, 0, sizeof(info));
-
- 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(journal->j_superblock->s_sequence);
- jbd_debug(1,
- "JBD: ignoring %d transaction%s from the journal.\n",
- dropped, (dropped == 1) ? "" : "s");
-#endif
- 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 int next_log_block;
- int err, success = 0;
- journal_superblock_t * sb;
- journal_header_t * tmp;
- struct buffer_head * bh;
- unsigned int sequence;
- int blocktype;
-
- /*
- * 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();
-
- /* 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 %u/%u\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 %u\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 int 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 %u in log\n",
- err, io_block);
- } else {
- unsigned int 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 *)nbh->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 int 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;
-}
Code Review / kvmfornfv.git / blobdiff