recovery.c File Reference

#include "jfs_user.h"

Include dependency graph for recovery.c:

Go to the source code of this file.

Classes
struct	recovery_info

Macros
#define	wrap(journal, var)

Enumerations
enum	passtype { PASS_SCAN , PASS_REVOKE , PASS_REPLAY }

Functions
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 *)
static int	jread (struct buffer_head **bhp, journal_t *journal, unsigned int offset)
static int	count_tags (struct buffer_head *bh, int size)
int	journal_recover (journal_t *journal)
int	journal_skip_recovery (journal_t *journal)

Macro Definition Documentation

wrap

#define wrap	(		journal,
			var
	)

Value:

do {                                    \
    if (var >= (journal)->j_last)                   \
        var -= ((journal)->j_last - (journal)->j_first);    \
} while (0)

Definition at line 207 of file recovery.c.

Enumeration Type Documentation

passtype

enum passtype

Enumerator
PASS_SCAN
PASS_REVOKE
PASS_REPLAY

Definition at line 41 of file recovery.c.

{PASS_SCAN, PASS_REVOKE, PASS_REPLAY};

Function Documentation

count_tags()

static int count_tags ( struct buffer_head *  bh, int  size  )

static

Definition at line 182 of file recovery.c.

{
    char *          tagp;
    journal_block_tag_t *   tag;
    int         nr = 0;
 
    tagp = &bh->b_data[sizeof(journal_header_t)];
 
    while (((int)(tagp - bh->b_data) + (int)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;
}

Referenced by do_one_pass().

do_one_pass()

static int do_one_pass ( journal_t *  journal, struct recovery_info *  info, enum passtype  pass  )

static

Definition at line 311 of file recovery.c.

{
    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();
 
        /* 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 (((int)(tagp - bh->b_data) + (int)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;
}

Referenced by journal_recover(), and journal_skip_recovery().

journal_recover()

int journal_recover

(

journal_t *

journal

)

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.

Definition at line 225 of file recovery.c.

{
    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(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);
    sync_blockdev(journal->j_fs_dev);
    return err;
}

Referenced by journal_load().

journal_skip_recovery()

int journal_skip_recovery

(

journal_t *

journal

)

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.

Definition at line 282 of file recovery.c.

{
    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);
        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;
}

Referenced by journal_wipe().

jread()

static int jread ( struct buffer_head **  bhp, journal_t *  journal, unsigned int  offset  )

static

Definition at line 132 of file recovery.c.

{
    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;
}

Referenced by do_one_pass().

scan_revoke_records()

static int scan_revoke_records ( journal_t *  journal, struct buffer_head *  bh, tid_t  sequence, struct recovery_info *  info  )

static

Definition at line 571 of file recovery.c.

{
    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;
}

Referenced by do_one_pass().