1 files changed, 609 insertions, 0 deletions

diff --git a/fs/jbd2/recovery.c b/fs/jbd2/recovery.c
new file mode 100644
index 000000000000..9f10acafaf70
--- /dev/null
+++ b/fs/jbd2/recovery.c
@@ -0,0 +1,609 @@
+/*
+ * 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/jbd2.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 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 = jbd2_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 long blocknr;
+        struct buffer_head *bh;
+
+        *bhp = NULL;
+
+        if (offset >= journal->j_maxlen) {
+                printk(KERN_ERR "JBD: corrupted journal superblock\n");
+                return -EIO;
+        }
+
+        err = jbd2_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(journal_t *journal, struct buffer_head *bh)
+{
+        char *                  tagp;
+        journal_block_tag_t *   tag;
+        int                     nr = 0, size = journal->j_blocksize;
+        int                     tag_bytes = journal_tag_bytes(journal);
+
+        tagp = &bh->b_data[sizeof(journal_header_t)];
+
+        while ((tagp - bh->b_data + tag_bytes) <= size) {
+                tag = (journal_block_tag_t *) tagp;
+
+                nr++;
+                tagp += tag_bytes;
+                if (!(tag->t_flags & cpu_to_be32(JBD2_FLAG_SAME_UUID)))
+                        tagp += 16;
+
+                if (tag->t_flags & cpu_to_be32(JBD2_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)
+
+/**
+ * jbd2_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 jbd2_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;
+
+        jbd2_journal_clear_revoke(journal);
+        sync_blockdev(journal->j_fs_dev);
+        return err;
+}
+
+/**
+ * jbd2_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 jbd2_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 inline unsigned long long read_tag_block(int tag_bytes, journal_block_tag_t *tag)
+{
+        unsigned long long block = be32_to_cpu(tag->t_blocknr);
+        if (tag_bytes > JBD_TAG_SIZE32)
+                block |= (u64)be32_to_cpu(tag->t_blocknr_high) << 32;
+        return block;
+}
+
+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;
+        int                     tag_bytes = journal_tag_bytes(journal);
+
+        /* 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))
+                               / tag_bytes);
+
+        /*
+         * 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(JBD2_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 JBD2_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(journal, bh);
+                                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 + tag_bytes)
+                               <= 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 long blocknr;
+
+                                        J_ASSERT(obh != NULL);
+                                        blocknr = read_tag_block(tag_bytes,
+                                                                 tag);
+
+                                        /* If the block has been
+                                         * revoked, then we're all done
+                                         * here. */
+                                        if (jbd2_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 & JBD2_FLAG_ESCAPE) {
+                                                *((__be32 *)bh->b_data) =
+                                                cpu_to_be32(JBD2_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 += tag_bytes;
+                                if (!(flags & JBD2_FLAG_SAME_UUID))
+                                        tagp += 16;
+
+                                if (flags & JBD2_FLAG_LAST_TAG)
+                                        break;
+                        }
+
+                        brelse(bh);
+                        continue;
+
+                case JBD2_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 JBD2_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)
+{
+        jbd2_journal_revoke_header_t *header;
+        int offset, max;
+        int record_len = 4;
+
+        header = (jbd2_journal_revoke_header_t *) bh->b_data;
+        offset = sizeof(jbd2_journal_revoke_header_t);
+        max = be32_to_cpu(header->r_count);
+
+        if (JBD2_HAS_INCOMPAT_FEATURE(journal, JBD2_FEATURE_INCOMPAT_64BIT))
+                record_len = 8;
+
+        while (offset + record_len <= max) {
+                unsigned long long blocknr;
+                int err;
+
+                if (record_len == 4)
+                        blocknr = be32_to_cpu(* ((__be32 *) (bh->b_data+offset)));
+                else
+                        blocknr = be64_to_cpu(* ((__be64 *) (bh->b_data+offset)));
+                offset += record_len;
+                err = jbd2_journal_set_revoke(journal, blocknr, sequence);
+                if (err)
+                        return err;
+                ++info->nr_revokes;
+        }
+        return 0;
+}